Electromechanical Coupling in the Feed System with High Speed and High Acceleration

2013 ◽  
Vol 49 (06) ◽  
pp. 2 ◽  
Author(s):  
Bingheng LU
Keyword(s):  
High Speed ◽  
Electromechanical Coupling ◽  
Feed System ◽  
High Acceleration

scholarly journals Monitoring and Modeling Railway Structures on High-Speed Lines with Asphalt Concrete Underlay: A Study on the Bretagne–Pays de la Loire Line

2020 ◽  
Vol 2674 (12) ◽  
pp. 600-607
Author(s):  
Diana Khairallah ◽  
Olivier Chupin ◽  
Juliette Blanc ◽  
Pierre Hornych ◽  
Jean-Michel Piau ◽  
...  
Keyword(s):  
Asphalt Concrete ◽  
High Speed ◽  
Large Scale ◽  
Strain Gages ◽  
Railway Transportation ◽  
Dynamic Stresses ◽  
High Speed Railway ◽  
High Frequencies ◽  
High Acceleration ◽  
High Speed Trains

The design and durability of high-speed railway lines is a major challenge in the field of railway transportation. In France, 40 years of feedback on the field behavior of ballasted tracks led to improvements in the design rules. However, the settlement and wear of ballast, caused by dynamic stresses at high frequencies, remains a major problem on high-speed tracks leading to high maintenance costs. Studies have shown that this settlement is linked to the high acceleration produced in the ballast layer by high-speed trains traveling on the track, disrupting the granular assembly. The “Bretagne–Pays de la Loire” high-speed line (BPL HSL), with its varied subgrade conditions, represents the first large-scale application of asphalt concrete (GB) as the ballast sublayer. This line includes 77 km of conventional track with a granular sublayer of unbound granular material (UGM) and 105 km of track with an asphalt concrete sublayer under the ballast. During construction, instruments such as accelerometers, anchored deflection sensors, and strain gages, among others, were installed on four sections of the track. This paper examines the instrumentation as well as the acquisition system installed on the track. The data processing is explained first, followed by a presentation of the ViscoRail software, developed for modeling railway tracks. The bituminous section’s behavior and response is modeled using a multilayer dynamic response model, implemented in the ViscoRail software. A good match between experimental and calculated results is highlighted.

scholarly journals 15 Years MR-encephalography

2020 ◽  
Author(s):  
Juergen Hennig ◽  
Vesa Kiviniemi ◽  
Bruno Riemenschneider ◽  
Antonia Barghoorn ◽  
Burak Akin ◽  
...  
Keyword(s):  
Time Domain ◽  
High Speed ◽  
Direct Detection ◽  
Principal Component ◽  
Isotropic Resolution ◽  
High Acceleration Factor ◽  
Spiral Trajectory ◽  
Time Domain Data ◽  
High Acceleration ◽  
The Time Domain

Abstract Objective This review article gives an account of the development of the MR-encephalography (MREG) method, which started as a mere ‘Gedankenexperiment’ in 2005 and gradually developed into a method for ultrafast measurement of physiological activities in the brain. After going through different approaches covering k-space with radial, rosette, and concentric shell trajectories we have settled on a stack-of-spiral trajectory, which allows full brain coverage with (nominal) 3 mm isotropic resolution in 100 ms. The very high acceleration factor is facilitated by the near-isotropic k-space coverage, which allows high acceleration in all three spatial dimensions. Methods The methodological section covers the basic sequence design as well as recent advances in image reconstruction including the targeted reconstruction, which allows real-time feedback applications, and—most recently—the time-domain principal component reconstruction (tPCR), which applies a principal component analysis of the acquired time domain data as a sparsifying transformation to improve reconstruction speed as well as quality. Applications Although the BOLD-response is rather slow, the high speed acquisition of MREG allows separation of BOLD-effects from cardiac and breathing related pulsatility. The increased sensitivity enables direct detection of the dynamic variability of resting state networks as well as localization of single interictal events in epilepsy patients. A separate and highly intriguing application is aimed at the investigation of the glymphatic system by assessment of the spatiotemporal patterns of cardiac and breathing related pulsatility. Discussion MREG has been developed to push the speed limits of fMRI. Compared to multiband-EPI this allows considerably faster acquisition at the cost of reduced image quality and spatial resolution.

Dynamic and Compliant Characteristics of a Cartesian-Guided Tripod Machine

2004 ◽  
Vol 128 (2) ◽  
pp. 494-502 ◽  
Author(s):  
Jeng-Shyong Chen ◽  
Wei-Yao Hsu
Keyword(s):  
High Speed ◽  
Degrees Of Freedom ◽  
Mechanical Vibration ◽  
Maximum Amplitude ◽  
High Gain ◽  
Velocity Change ◽  
Flexible Mode ◽  
Look Ahead ◽  
High Acceleration ◽  
Acceleration And Deceleration

This paper is focused on the dynamic and compliant characteristics of a three-axis parallel kinematic machine called a Cartesian-guided tripod (CGT), which has a passive leg locking the platform three rotational degrees of freedom. Because no constraint mechanism is perfect with infinite rigidity, a compliance model has been developed to determine the maximum amplitude of the passive-leg parasitic motions using given loads. System compliance, dynamic characteristics, vibration modes, and servo-contouring errors of the CGT driving system have also been evaluated under high-speed machining conditions. The nonlinear dynamic effects, such as inertia and gravity, can be controlled within acceptable accuracy using the high-gain servo-feedback control techniques. The CGT dominant flexible mode occurs on the horizontal platform-leg vibration. The platform-leg flexible mode can produce significant jerk-induced mechanical vibration on the platform when a sudden velocity change is commanded. Look-ahead Cartesian-based path acceleration and deceleration control was found to be an efficient tool to reduce the jerk-induced mechanical vibration, although the CGT was drive controlled at the joint level. It was found that at high acceleration application, such as high-speed mold and die machining, the elastic elongation of the driving leg caused by the high acceleration force became the dominant contouring error sources.

Simulation and Experimental Investigation of Stiffness of the High Acceleration Linear Feed Drives

2010 ◽  
Vol 97-101 ◽  
pp. 3113-3119
Author(s):  
Ping Ma ◽  
Cheng Xiang Liao ◽  
Zhen Hui Chen ◽  
Gong Zhen
Keyword(s):  
High Speed ◽  
Dynamic Performance ◽  
Great Influence ◽  
Linear Motor ◽  
Current Loop ◽  
Linear Induction Motor ◽  
Feed Drive ◽  
Feed Drives ◽  
High Acceleration ◽  
Motorized Spindles

In high speed machining, the feed drives with high velocity and high acceleration are necessary to make full use of the capacities of the high speed motorized spindles. The linear motor feed drive eliminates any mid- transmitting mechanism, which cause achieved the high acceleration. In this paper, the GD-Ⅲ linear induction motor feed drive is introduced, and its controller is modeled and its stiffness has been investigated with simulation program MATLAB & SIMULINK. The influence of the parameters of the controller on the dynamic performance has also been analyzed. The simulation shows that the positional loop proportional gain kv, velocity proportional gain kp, velocity loop integral time constant Tn and the current loop proportional gain kpi have great influence on the dynamics of the linear motor feed drive. In the end, the simulation is verified by the experimental results.

Adaptive Synchronized Control for a Planar Parallel Manipulator: Theory and Experiments

2005 ◽  
Vol 128 (4) ◽  
pp. 976-979 ◽  
Author(s):  
Lu Ren ◽  
James K. Mills ◽  
Dong Sun
Keyword(s):  
Parallel Manipulator ◽  
High Speed ◽  
Control Method ◽  
Parametric Uncertainty ◽  
Synchronization Error ◽  
Tracking Accuracy ◽  
Unknown Parameters ◽  
High Acceleration ◽  
Planar Parallel Manipulator ◽  
Synchronized Control

In this paper, we develop a new control method, termed adaptive synchronized (A-S) control, for improving tracking accuracy of a P-R-R type planar parallel manipulator with parametric uncertainty. The novelty of A-S control, a combination of synchronized control and adaptive control, is in the application of synchronized control to a single parallel manipulator so that tracking accuracy is improved during high-speed, high-acceleration tracking motions. Through treatment of each chain as a submanipulator; the P-R-R manipulator is thus modeled as a multi-robot system comprised of three submanipulators grasping a common payload. Considering the geometry of the platform, these submanipulators are kinematically constrained and move in a synchronous manner. To solve this synchronization control problem, a synchronization error is defined, which represents the coupling effects among the submanipulators. With the employment of this synchronization error, tracking accuracy of the platform is improved. Simultaneously, the estimated unknown parameters converge to their true values through the use of a bounded-gain-forgetting estimator. Experiments conducted on the P-R-R manipulator demonstrate the validity of the approach.

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