A novel control strategy for the multi-step straightening process of long/extra-long linear guideways

2018 ◽  
Vol 233 (9) ◽  
pp. 2959-2975 ◽  
Author(s):  
Yongquan Zhang ◽  
Hong Lu ◽  
Xinbao Zhang ◽  
He Ling ◽  
Wei Fan ◽  
...  
Keyword(s):  
Control Strategy ◽  
Complex Shape ◽  
Helix Angle ◽  
Single Step ◽  
Integral Model ◽  
The Finite Element Method ◽  
Section Shape ◽  
Curvature Integral ◽  
Point Pressure ◽  
Feeding Process

The straightening process for a linear guideway with particular cross-section shape is normally conducted by the three-point pressure bending method. However, the single-step straightening process (SSSP) of a long/extra-long linear guideway may make the workpiece from a single-curvature curve into a more complex shape. Due to these limitations of SSSP, a quantitative control strategy for the multi-step straightening process (MSSP) of a long/extra-long linear guideway is proposed in this paper based on the straightening principle of SSSP. Firstly, the predictive models for straightening stroke and helix angle after unloading with respect to SSSP are developed based on the elasto-plastic theory and curvature integral model. Depending on the established analytical model for SSSP, the MSSP is then mathematically modelled to obtain corresponding straightening parameters considering feeding process, clamping process and straightening process. Besides, the finite element method has been applied to validate the developed mathematical model for the MSSP. Taking the approach of a linear guideway as an example, the experimental results have also shown that the proposed control strategy is appropriate for the MSSP of a long/extra-long linear guideway.

scholarly journals Development of a Controlled Continuous Low-Dose Feeding Process

2021 ◽  
Vol 22 (7) ◽  
Author(s):  
Sara Fathollahi ◽  
Julia Kruisz ◽  
Stephan Sacher ◽  
Jakob Rehrl ◽  
M. Sebastian Escotet-Espinoza ◽  
...  
Keyword(s):  
Control Strategy ◽  
Small Particle ◽  
Feed Rate ◽  
Low Dose ◽  
Particle System ◽  
High Density ◽  
Displacement Rate ◽  
Set Point ◽  
Relative Standard ◽  
Feeding Process

AbstractThis paper proposes a feed rate control strategy for a novel volumetric micro-feeder, which can accomplish low-dose feeding of pharmaceutical raw materials with significantly different powder properties. The developed feed-forward control strategy enables a constant feed rate with a minimum deviation from the set-point, even for materials that are typically difficult to accurately feed (e.g., due to high cohesion or low density) using conventional continuous feeders. Density variations observed during the feeding process were characterized via a displacement feed factor profile for each powder. The characterized effective displacement density profile was applied in the micro-feeder system to proactively control the feed rate by manipulating the powder displacement rate (i.e., computing the feed rate from the powder displacement rate). Based on the displacement feed factor profile, the feed rate can be predicted during the feeding process and at any feed rate set-point. Three pharmaceutically relevant materials were used for the micro-feeder evaluation: di-calcium phosphate (large-particle system, high density), croscarmellose sodium (small-particle system, medium density), and barium sulfate (very small-particle <10 μm, high density). A significant improvement in the feeding performance was achieved for all investigated materials. The feed rate deviation from the set-point and its relative standard deviation were minimal compared to operations without the control strategy.

Control Strategy for Urea-SCR System in Single Step Load Transition

2006 ◽  
Author(s):  
Ryota Nakayama ◽  
Tazuki Watanabe ◽  
Keishi Takada ◽  
Matsuo Odaka ◽  
Jin Kusaka ◽  
...  
Keyword(s):  
Control Strategy ◽  
Single Step ◽  
Scr System

scholarly journals Numerical Investigation of a Process Control for the Roller Levelling Process Based on a Force Measurement

2016 ◽  
Vol 854 ◽  
pp. 249-254 ◽  
Author(s):  
Markus Grüber ◽  
Gerhard Hirt
Keyword(s):  
Process Control ◽  
Control Strategy ◽  
Material Properties ◽  
Force Measurement ◽  
Control Strategies ◽  
Fe Model ◽  
The Finite Element Method ◽  
Feed Forward Control ◽  
Strip Length ◽  
Control Curves

When processing conventional semi-finished metal strips, distinctive changes in the material properties along the strip length are unavoidable. The roller levelling process is sensitive to changes of those strip characteristics. Thus, a process control allowing for an online adaption of the roller levelling machine according to the actual strip characteristics is highly desirable. In order to enable a precise process layout, the calculation by the Finite Element Method (FEM) provides a suited strategy. Furthermore, the coupling of user-subroutines to an FE code offers the possibility to implement and test respective control strategies. This work proposes a control strategy that is based on a force measurement in the first load triangle of a levelling machine. A first FE model including a feedback control is used to calculate the dependence between the force in the first load triangle and the roll intermesh in the last load triangle leading to a flat sheet. The results are transferred to meta models – so called control curves – that give a direct relationship between the measured force and the roll intermesh. Within a second FE setup a feed-forward control based on these control curves is implemented and the proposed control strategy is investigated for varying yield strengths along the strip length. Thus, the time consuming FE simulations that are necessary to obtain the control curves are decoupled from the actual levelling process. According to the obtained results, the introduced approach is able to improve the sheet flatness for thin sheets when a change in the material properties occurs.

In-Situ Experiments to Estimate the Performance Characteristics of a Double-Step Helical-Bladed Hydrokinetic Turbine

2017 ◽  
Author(s):  
Parag K. Talukdar ◽  
Vinayak Kulkarni ◽  
Amarendra K. Das ◽  
Santosha K. Dwivedy ◽  
Sashindra Kumar Kakoty ◽  
...  
Keyword(s):  
Electricity Generation ◽  
Helix Angle ◽  
Single Step ◽  
Performance Characteristics ◽  
Double Step ◽  
Hydrokinetic Turbines ◽  
Hydrokinetic Turbine ◽  
Solidity Ratio ◽  
In Situ Experiments

With the rising level of greenhouse gas emissions and fuel prices, the hydrokinetic turbines have become increasingly popular for electricity generation in rural and remote areas teemed with small river streams. Such lift-based helical-bladed hydrokinetic turbines were invented over a decade ago, however, they could not find their wide application in commercial power generation. The present investigation deals with the in-situ experiments of a double-step three-bladed helical hydrokinetic turbine for possible electricity generation. Further, its performance is compared with that of a conventional single-step helical-bladed turbine. The main parameters that influence the performance of a helical-bladed hydro turbine are solidity ratio, blade wrap ratio, helix angle, blade profile and number of blades. In the present work, the helical NACA 0022 bladed turbines with solidity ratio of 0.20 and blade wrap ratio of 1.0 have been developed. The developed single and double-step configurations have been field-tested in the Brahmaputra river and their performance characteristics are estimated at different mechanical loading conditions using mechanical dynamometer.

scholarly journals Combustion phasing modeling and control for compression ignition engines with high dilution and boost levels

2018 ◽  
Vol 233 (7) ◽  
pp. 1834-1850 ◽  
Author(s):  
Wenbo Sui ◽  
Carrie M Hall
Keyword(s):  
Steady State ◽  
Control Strategy ◽  
Internal Combustion Engines ◽  
Integral Model ◽  
Loop Control ◽  
Model Based Control ◽  
Model Based ◽  
Crank Angle Degree ◽  
Crank Angle ◽  
Phasing Control

Because fuel efficiency is significantly affected by the timing of combustion in internal combustion engines, accurate control of combustion phasing is critical. In this paper, a nonlinear combustion phasing model is introduced and calibrated, and both a feedforward model–based control strategy and an adaptive model–based control strategy are investigated for combustion phasing control. The combustion phasing model combines a knock integral model, burn duration model, and a Wiebe function to predict the combustion phasing of a diesel engine. This model is simplified to be more suitable for combustion phasing control and is calibrated and validated using simulations and experimental data that include conditions with high exhaust gas recirculation fractions and high boost levels. Based on this model, an adaptive nonlinear model–based controller is designed for closed-loop control, and a feedforward model–based controller is designed for open-loop control. These two control approaches were tested in simulations. The simulation results show that during transient changes, the CA50 (the crank angle at which 50% of the mass of fuel has burned) can reach steady state in no more than five cycles and the steady-state errors are less than ±0.1 crank angle degree for adaptive control and less than ±0.5 crank angle degree for feedforward model–based control.

Understanding the Formation Mechanism of Residual Stress during Precision Glass Moulding

2014 ◽  
Vol 626 ◽  
pp. 182-186
Author(s):  
Wei Dong Liu ◽  
Liang Chi Zhang
Keyword(s):  
Residual Stresses ◽  
Formation Mechanism ◽  
Single Step ◽  
Raw Material ◽  
Complex Geometries ◽  
The Finite Element Method ◽  
Optical Lens ◽  
Processing Program ◽  
Rate Of Cooling ◽  
Selection Of

Precision glass moulding is a technique that enables the production of optical lenses of complex geometries in a single step. However, it has been reported that the product quality highly depends on the properties of a raw material, the design of a die, and the selection of a processing program. This paper aims to reveal the formation mechanism of the residual stresses by optical lens moulding. To this end, a modulus-based constitutive model was developed to integrate with the deformation and stress analyses by the finite element method. The investigation showed that the residual stresses are caused by the variability and heterogeneity of thermal expansion in a lens, but that they can be reduced effectively by decreasing the rate of cooling within the stage from the molding temperature to the glass transition temperature.

Prediction of Maximum Forging Load and Billet Volume Using FEM of a Near Net-Shaped Helical-Bevel Gear Forging

2014 ◽  
Vol 939 ◽  
pp. 563-569
Author(s):  
Tung Sheng Yang ◽  
Jia Hua Liang ◽  
Jie Chang
Keyword(s):  
Finite Element ◽  
Effective Strain ◽  
Helix Angle ◽  
Bevel Gear ◽  
The Finite Element Method ◽  
Element Analysis ◽  
Power Requirement ◽  
Near Net Shape ◽  
Warm Forging ◽  
Forging Load

This study applies the finite element method (FEM) to predict maximum forging load, billet volume and effective strain in near net-shaped helical-bevel gear forging. Finite element analysis is also applied when designing the near net-shape of a helical-bevel gear, a reverse forming approach to acquire the initial dimensions of the billet based on the forward forging of the helical-bevel gear. Maximum forging load, billet volume and effective strain are determined for different process parameters, such as modules, number of teeth, helix angle and workpiece temperature of the helical bevel gear forging, using the FEM. Finally, the prediction of the power requirement and billet dimensions for the helical-bevel gear warm forging are determined.

scholarly journals The Use Of Multifrequency Induction Heating For Temperature Distribution Control

2015 ◽  
Vol 60 (2) ◽  
pp. 721-725 ◽  
Author(s):  
A. Smalcerz
Keyword(s):  
Temperature Distribution ◽  
Complex Shape ◽  
Temperature Fields ◽  
The Finite Element Method ◽  
Uniform Temperature ◽  
Temperature Field Distribution ◽  
Practical Applications ◽  
Gear Wheels ◽  
Calculation Software ◽  
Frequency Heating

AbstractThe paper presents possibilities of controlling temperature field distribution in inductively heated charge. The change of its distribution was obtained using the sequential one-, two-, and three-frequency heating. The study was conducted as a multi-variant computer simulation of hard coupled electromagnetic and temperature fields. For the analysis, a professional calculation software package utilizing the finite element method, Flux 3D, was used. The problem of obtaining an appropriate temperature distribution in the heated charge of a complex shape is very important in many practical applications. A typical example is hardening of gear wheels. For such an application, it is necessary to obtain (on the surface and at a desired depth) an uniform temperature distribution on the tooth face, top land and bottom land of the gear. The obtained temperature should have proper distribution and value. Such a distribution is very difficult to achieve.

scholarly journals The Exoskeleton Balance Assistance Control Strategy Based on Single Step Balance Assessment

2019 ◽  
Vol 9 (5) ◽  
pp. 884 ◽  
Author(s):  
Fusheng Zha ◽  
Wentao Sheng ◽  
Wei Guo ◽  
Shiyin Qiu ◽  
Xin Wang ◽  
...  
Keyword(s):  
Control Strategy ◽  
Control Experiment ◽  
Assessment Method ◽  
Single Step ◽  
Assessment Methods ◽  
Balance Assessment ◽  
Balance Recovery ◽  
Exoskeleton Robot ◽  
Human Balance ◽  
Balance Loss

A novel balance assistance control strategy of a hip exoskeleton robot was proposed in this paper. The organic fusion of the human balance assessment and the exoskeleton balance assistance control strategy are the assurance of balance recovery. However, currently there are few human balance assessment methods that are suitable for detecting balance loss during standing and walking, and very little research has focused on exoskeleton balance recovery control. In this paper, a single step balance assessment method was proposed first, and then based on this method an "assist-as-needed" balance assistance control strategy was established. Finally, the exoskeleton balance assistance control experiment was carried out. The experiment results verified the effectiveness of the single balance assessment method and the active balance assistance control strategy.

Sign in / Sign up

Export Citation Format

Share Document