A Self-Correcting Approach for the Bending of Metal Parts

2012 ◽  
Vol 504-506 ◽  
pp. 907-912 ◽  
Author(s):  
Ulf Damerow ◽  
Mikhail Borzykh ◽  
Werner Homberg ◽  
Ansgar Trächtler
Keyword(s):  
Process Parameters ◽  
Control Strategy ◽  
Control Strategies ◽  
Testing Machine ◽  
The Self ◽  
Loop Control ◽  
Geometrical Properties ◽  
Metal Parts ◽  
Experimental Tool ◽  
The University

During the manufacture of metal parts, geometrical deviations can appear. The reasons for this can be a variation in the properties of the semi-finished product, or wear phenomena on the punch-bending machine itself or on the punch-bending tool. When geometrical deviations appear, the process parameters normally have to be adjusted manually. The choice of the most appropriate process parameters is currently based on the operator's experience. Unfortunately, this is a time-consuming and expensive procedure right at the early stages of a production scenario. In addition, the trend towards reduced part sizes with tight tolerances, made of high strength materials, is drastically increasing the requirements regarding the production process. In order to reduce the scrap rate and the setup time for production scenarios, it is necessary to implement corrective action during the process by means of a special control strategy. A self-correcting control strategy based on a closed-loop control approach is thus under development at the University of Paderborn. The first step in this strategy involved conducting simulations is to identify those process variables, e.g. the strength or the geometrical properties of the material, which have a significant influence on the process. Once correlations between input and output variables had been established, different self-correcting control strategies were set up. To validate the simulation and to test the quality of the self-correcting control strategies, a special experimental tool, mapping the most important bending operations, was constructed at the University of Paderborn. The experimental tool is equipped with an additional measurement device and can be operated on a universal testing machine. Finally, the self-correcting control strategies were tested under production conditions on the original tool in order to take any additional influences of the punch-bending machine into consideration. In this paper, recent investigations are presented that were conducted in a collaborative project at the University of Paderborn together with two industrial partners. The results of the correlation between the variables governing the process, the development of a suitable measurement method, and a first approach to a self-correcting control strategy are set out.

scholarly journals Rule-Based Control Strategy to Increase Photovoltaic Self-Consumption of a Modulating Heat Pump Using Water Storages and Building Mass Activation

Energies ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 6282
Author(s):  
Maria Pinamonti ◽  
Alessandro Prada ◽  
Paolo Baggio
Keyword(s):  
Boundary Conditions ◽  
Heat Pump ◽  
Control Strategy ◽  
Control Strategies ◽  
Residential Buildings ◽  
Thermal Inertia ◽  
The Self ◽  
Thermal Mass ◽  
Climate Data ◽  
Rule Based

The use of photovoltaic (PV) energy in combination with heat pump systems for heating and cooling of residential buildings can lead to renewable energy self-consumption, reducing the energy required from the grid and the carbon footprint of the building uses. However, energy storage technologies and control strategies are essential to enhance the self-consumption level. This paper proposes and analyzes a new control strategy for the operation of a modulating air-source heat pump, based on the actual PV availability. The solar energy surplus is stored as thermal energy by the use of water tanks and the activation of the thermal capacitance of the building. The efficacy of the control strategy is evaluated considering different rule-based strategies, and different boundary conditions. The effect of climate data, building insulation level and thermal inertia are investigated and compared. The results show the efficacy of the proposed strategy to decrease up to 17% the amount of electricity purchased from the grid and to increase the self-consumption by 22%, considering a high-insulated building in Bolzano, Northern Italy. The thermal mass activation is found effective to increase the self-consumption of the system. Nonetheless, the achievable energy reduction depends largely on the building characteristics and the boundary conditions.

scholarly journals Comparison of Feedback Control Strategies for Operation of Granulation Loops

2021 ◽  
Vol 50 (4) ◽  
pp. 736-751
Author(s):  
Ludmila Vesjolaja ◽  
Bjørn Glemmestad ◽  
Bernt Lie
Keyword(s):  
Feedback Control ◽  
Control Strategy ◽  
Fine Particles ◽  
Control Strategies ◽  
Pi Controller ◽  
Oscillatory Behavior ◽  
Double Loop ◽  
Oscillatory Behaviour ◽  
Loop Control ◽  
Median Diameter

Granulation is a particle enlargement process during which fine particles or atomizable liquids are converted into granules via a series of complex granulation mechanisms. In this paper, two feedback control strategies are implemented to make granulation loop processes more steady to operate, i.e., to suppress oscillatory behavior in the produced granule sizes. In the first control strategy, a classical proportional-integral (PI) controller is used, while in the second, a double-loop control strategy is used to control the median diameter of the granules leaving the granulator. The simulation results showed that using the proposed control design for the granulation loop can eliminate the oscillatory behaviour in the produced granule median diameter and make granulation loop processes more steady to operate. A comparison between the two proposed control strategies showed that it is preferable to use the double-loop control strategy.

Laser-Beam Fusion of Predeposited Metal Powder for Layered Manufacturing: Modeling, Simulation, and Experiment

1998 ◽  
Author(s):  
Vladimir Yevko ◽  
Gene Zak ◽  
Chul B. Park ◽  
Tom W. Coyle ◽  
Beno Benhabib
Keyword(s):  
Laser Beam ◽  
Metal Powder ◽  
Process Parameters ◽  
Powder Layer ◽  
Geometrical Properties ◽  
Metal Parts ◽  
Process Simulations ◽  
Simulation And Experiment ◽  
Laser Beam Scanning ◽  
Good Agreement

Abstract Current commercial Rapid Prototyping (RP) systems can be used for fabricating layered models for subsequent creation of fully-dense metal parts using investment casting. Due to increased demand for shortened product development cycles, however, there exists a demand to rapidly create functional fully-dense metal parts without hard tooling. A possible solution to this problem is direct layered Rapid Manufacturing (RM) of such parts, for example, via laser-beam fusion of the metal powder. The RM process proposed herein is based on this approach. It involves selective laser-beam scanning of a predeposited metal-powder layer, forming fully-dense claddings, as the basic building block of individual layers. This paper specifically addresses only one of the fundamental issues of the proposed RM process, namely the fabrication of single claddings. Our theoretical investigation of the influence of the process parameters on cladding’s geometrical properties employed thermal modeling and computer process simulation. Numerous experiments, involving fabrication of single claddings, were also carried out with varying process parameters. Comparisons of the process simulations and experimental results showed good agreement in terms of overall trends.

Influence of closed loop control on microbial diversity in a nitrification process

2006 ◽  
Vol 53 (4-5) ◽  
pp. 85-93 ◽  
Author(s):  
D. Bougard ◽  
N. Bernet ◽  
P. Dabert ◽  
J.P. Delgenes ◽  
J.P. Steyer
Keyword(s):  
Microbial Diversity ◽  
Active Control ◽  
Control Strategy ◽  
Closed Loop ◽  
Control Strategies ◽  
Closed Loop Control ◽  
Loop Control ◽  
Nitrification Process ◽  
Term Evaluation

This paper compares two control strategies for a nitrification process. The objective is to achieve partial nitrification and thus to accumulate nitrite instead of nitrate. To this end, change in temperature setpoint and active control of oxygen and ammonia concentrations are evaluated in the long term. Evaluation is made on the control performances that are obtained, but also – and more importantly – on the microbial diversity. In particular, it is shown that the combined oxygen and ammonia control strategy is more appropriate since shift in the temperature setpoint strongly affects the composition of the microbial ecosystem present in the reactor whereas active control of oxygen and ammonia does not.

Dynamic Simulation for Grid-Connected Inverters of Distributed Generation Based on DIgSILENT Software

2013 ◽  
Vol 291-294 ◽  
pp. 2042-2046
Author(s):  
Zhang Le Zhao ◽  
You Bing Zhang ◽  
Jun Qi
Keyword(s):  
Distributed Generation ◽  
Control Strategy ◽  
Control Method ◽  
Control Strategies ◽  
Simulation Models ◽  
Double Loop ◽  
Rotating Frame ◽  
Control Methods ◽  
Outer Loop ◽  
Loop Control

This paper introduces some typical control methods for the grid-connected inverters in the distributed generation (DG) systems, the double-loop control strategy is focused on and analyzed in detail. The proposed outer-loop control strategies are summarized. Meanwhile, the inner-loop control method established on dq rotating frame is introduced. The simulation models of the inverters for DG in the DIgSILENT software are introduced, and the simulations for the proposed control strategies are realized.

RESIDUAL CAPABILITIES OF HEMIPLEGIC PATIENTS TO RESTORE HAND FUNCTIONS VIA A NON-INVASIVE FUNCTIONAL ELECTRICAL STIMULATION SYSTEM

2006 ◽  
Vol 18 (05) ◽  
pp. 255-263
Author(s):  
YING-HAN CHIOU ◽  
JER-JUNN LUH ◽  
SHIH-CHING CHEN ◽  
JIN-SHIN LAI ◽  
TE-SON KUO
Keyword(s):  
Electrical Stimulation ◽  
Functional Electrical Stimulation ◽  
Control Strategy ◽  
Control Method ◽  
Control Strategies ◽  
Hand Function ◽  
Loop Control ◽  
Non Invasive ◽  
Hand Functions ◽  
Electrical Stimulator

Control strategies are the chief attraction in the field of rehabilitation engineering, and especially in a functional electrical stimulation (FES) system, a reliable control method is important for paralyzed patients to restore lost their functions. In this paper, we have presented a demonstration of the control strategy, which is based on the patient-driven loop, used in a non-invasive FES system for hand function restoration. With the patient-driven loop control, hemiplegic patients could use their residual capabilities, such as shoulder movements in their sound extremities, the myoelectric signals generated from different muscles, etc, to operate the FES system. Here we have chosen the most common and acceptable signals as the input sources, i.e. electromyographic (EMG) signals, to control a non-invasive FES system, generating the electrical stimuli to excite the paralyzed muscles. In addition, EMG signals recorded by the sensors in the electrical stimulator can serve both as the trigger of the system and as the adjustment of the electrical stimulation parameters, thereby improving the system's performance and reliability. From the experimental results, subjects can successfully use their residual capabilities to control the FES system and restore their lost hand functions as well. On the other hand, from the viewpoints of rehabilitation and psychology, hemiplegics will benefit greatly by using their residual capabilities to regain their lost functions. It is believed that the patient-driven loop control is very useful, not only for the FES system in this study, but also for other assistive devices. By the control strategy proposed in this paper, we deeply hope that patients will benefit greatly and regain their self-confidence.

scholarly journals Design, implementation, and control of a deformable manipulator robot based on a compliant spine

2020 ◽  
Vol 39 (14) ◽  
pp. 1604-1619 ◽  
Author(s):  
Thor Morales Bieze ◽  
Alexandre Kruszewski ◽  
Bruno Carrez ◽  
Christian Duriez
Keyword(s):  
Control Strategy ◽  
Lattice Structure ◽  
Numerical Models ◽  
Control Strategies ◽  
Optimization Methods ◽  
Loop Control ◽  
Beam Elements ◽  
And Control ◽  
Manipulator Robot ◽  
Inspection Task

This article presents the conception, the numerical modeling, and the control of a dexterous, deformable manipulator bio-inspired by the skeletal spine found in vertebrate animals. Through the implementation of this new manipulator, we show a methodology based on numerical models and simulations, that goes from design to control of continuum and soft robots. The manipulator is modeled using a finite element method (FEM), using a set of beam elements that reproduce the lattice structure of the robot. The model is computed and inverted in real-time using optimization methods. A closed-loop control strategy is implemented to account for the disparities between the model and the robot. This control strategy allows for accurate positioning, not only of the tip of the manipulator, but also the positioning of selected middle points along its backbone. In a scenario where the robot is piloted by a human operator, the command of the robot is enhanced by a haptic loop that renders the boundaries of its task space as well as the contact with its environment. The experimental validation of the model and control strategies is also presented in the form of an inspection task use case.

scholarly journals A Robust Nonlinear Control Strategy for Unsupported Paraplegic Standing Using Functional Electrical Stimulation: Controller Synthesis and Simulation

2020 ◽  
Vol 7 (2) ◽  
pp. 88-102
Author(s):  
Seyedeh Sakineh Ruhbakhsh ◽  
Hamid Reza Kobravi
Keyword(s):  
Electrical Stimulation ◽  
Functional Electrical Stimulation ◽  
Control Strategy ◽  
Center Of Pressure ◽  
Sliding Mode ◽  
Control Strategies ◽  
Adaptive Controller ◽  
Loop Control ◽  
Balance Dynamics ◽  
Stable Zone

Background: Functional electrical stimulation (FES) applies electrical pulses to paralyzed muscles to restore their function. Closed-loop control of an FES system, incorporating the control strategies, promises to improve the performance of FES systems. Therefore, the purpose of this paper is to design a new control strategy applicable to restoring the upright standing in paraplegic patients through FES. The control strategies proposed in the previous works based on controlling the angular joint position and none of them focused on controlling the center of pressure (CoP) dynamics directly. Since the CoP is representative of posture balance dynamics, in this study, the adopted FES based control strategy designed to control the CoP dynamics directly. Methods: In the proposed control strategy, two controllers determine the stimulation intensity of ankle muscles in a manner to restrict the CoP to a specific zone. According to the proposed strategy, until the CoP confined to the stable zone, an adaptive controller is active. When the CoP goes out of the stable zone, the adaptive controller is deactivated. Then, a sliding mode controller is activated instead of the adaptive controller. In this manner, not only the posture balance can be guaranteed, but also the emerged balance dynamics can be similar to the elicited balance dynamics in the healthy subjects. Results: In this study, extended evaluations carried out through the simulation studies. According to the achieved results, the proposed control strategy is not only robust against the external disturbances, but also insensitive to the initial postural conditions. Conclusion: The achieved results prove the acceptable performance of the proposed control strategy

HIV/AIDS Knowledge and Risk-Taking Behaviours among Youths at a University in Enugu, Nigeria

2018 ◽  
Vol 20 (1) ◽  
Author(s):  
Ada C. Nwaneri ◽  
Okwudili Callistus Ezike ◽  
Agnes N. Anarado ◽  
Ifeoma Ndubisi ◽  
Jane-Lovena Onyia-Pat
Keyword(s):  
Risk Taking ◽  
Control Strategies ◽  
Analysis Of Covariance ◽  
Cross Sectional ◽  
Awareness Campaigns ◽  
South Eastern ◽  
Risky Behaviours ◽  
Aids Knowledge ◽  
The University ◽  
Hiv Aids

 A national sentinel survey of 2006 shows that Enugu State in south-eastern Nigeria is the worst hit by HIV infections. Despite numerous control strategies having been implemented, the state was still reported by another national HIV sentinel survey in 2010 as the worst hit by HIV/AIDS within the zone, and that youths are the most affected. The researchers conducted a cross-sectional descriptive survey to assess the HIV/AIDS knowledge and risk-taking behaviours of youths at a federal university in Enugu, south-eastern Nigeria. They adopted a multistage sampling method to recruit 460 unmarried, consenting students between 15 and 30 years of age, from three faculties of the university. Almost 90 per cent of the university youths had a sound knowledge of key concepts related to HIV/AIDS; despite this, a subset (7.39%) still engaged in risk-taking behaviours. The major risky behaviours identified include having premarital sex, having multiple sexual partners, the sharing of shaving or razor blades, the use of public clippers and tribal marking. Although an analysis of variance demonstrated no significant relationship (t = −0.036) between university youths’ knowledge of HIV/AIDS and their related risk-taking behaviour, risky behaviours were found to be more (13%) among respondents who had insufficient or incorrect knowledge of the disease. An analysis of covariance, however, showed that gender and socio-economic backgrounds were not determinants of the HIV/AIDS risk-taking behaviours of these youths. Therefore, factors such as attitude or culture are areas that should be focused on, and should then, along with educational awareness campaigns, help to reduce the spread and prevalence of the disease.

Control Strategies for a Highly Loaded Biological Ammonia Elimination Process

1993 ◽  
Vol 28 (11-12) ◽  
pp. 531-538 ◽  
Author(s):  
B. Teichgräber
Keyword(s):  
Closed Loop ◽  
Control Strategies ◽  
Level Control ◽  
Sludge Dewatering ◽  
Loop Control ◽  
Reject Water ◽  
Line Measurement ◽  
Control Pattern ◽  
On Line ◽  
Treatment Facilities

A nitrification/denitrification process was applied to reject water treatment from sludge dewatering at Bottrop central sludge treatment facilities of the Emschergenossenschaft. On-line monitoring of influent and effluent turbidity, closed loop control of DO and pH, and on-line monitoring of nitrogen compounds were combined to a three level control pattern. Though on-line measurement of substrate and product showed substantial response time it could be used to operate nitrification/denitrification within process boundaries.

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