A Transfer Function Description of Sheet Metal Forming for Process Control

1991 ◽  
Vol 113 (1) ◽  
pp. 44-52 ◽  
Author(s):  
R. D. Webb ◽  
D. E. Hardt
Keyword(s):  
Transfer Function ◽  
Process Control ◽  
Spatial Frequency ◽  
Sheet Metal ◽  
Closed Loop ◽  
Control Method ◽  
Three Dimensional ◽  
Identification Problem ◽  
Complex Deformation ◽  
Domain Transfer

Three-dimensional forming of sheet metal parts is typically accomplished using one or two shaped tools (dies) that impart the necessary complex curvature and induce sufficient in-plane strain for part strength and shape stability. This research proposes a method of applying closed-loop process control concepts to sheet forming in a manner that automatically converges upon the appropriate tooling design. The problem of controlling complex deformation is reduced to a system identification problem where the die-part transformation is developed as a spatial frequency domain transfer function. This transfer function is simply the ratio of the measured change in spatial frequency content of the part and the die. It is then shown that such a transfer function can be used to implement closed-loop process control via rapid die redesign. Axisymmetric forming experiments are presented that establish the appropriateness of the linear transfer function description (via a test of superposition) and demonstrate the convergence properties of the proposed control method.

Density-based discrimination of protein and RNA in the ribosome

1992 ◽  
Vol 50 (1) ◽  
pp. 464-465
Author(s):  
Joachim Frank
Keyword(s):  
Transfer Function ◽  
Spatial Frequency ◽  
Three Dimensional ◽  
Wiener Filter ◽  
Dark Field Image ◽  
Dark Field ◽  
Frequency Range ◽  
Bright Field ◽  
Contrast Transfer Function ◽  
Pass Filter

Cryo-electron microscopy combined with single-particle reconstruction techniques has allowed us to form a three-dimensional image of the Escherichia coli ribosome.In the interior, we observe strong density variations which may be attributed to the difference in scattering density between ribosomal RNA (rRNA) and protein. This identification can only be tentative, and lacks quantitation at this stage, because of the nature of image formation by bright field phase contrast. Apart from limiting the resolution, the contrast transfer function acts as a high-pass filter which produces edge enhancement effects that can explain at least part of the observed variations. As a step toward a more quantitative analysis, it is necessary to correct the transfer function in the low-spatial-frequency range. Unfortunately, it is in that range where Fourier components unrelated to elastic bright-field imaging are found, and a Wiener-filter type restoration would lead to incorrect results. Depending upon the thickness of the ice layer, a varying contribution to the Fourier components in the low-spatial-frequency range originates from an “inelastic dark field” image. The only prospect to obtain quantitatively interpretable images (i.e., which would allow discrimination between rRNA and protein by application of a density threshold set to the average RNA scattering density may therefore lie in the use of energy-filtering microscopes.

Spatial Frequency Domain Analysis of Heat Transfer in Microelectronic Chips With Applications to Temperature Aware Computing

2007 ◽  
Author(s):  
Keivan Etessam-Yazdani ◽  
Hendrik F. Hamann ◽  
Mehdi Asheghi
Keyword(s):  
Transfer Function ◽  
Spatial Frequency ◽  
Frequency Domain ◽  
Thermal Power ◽  
Three Dimensional ◽  
Heat Removal ◽  
Frequency Domain Analysis ◽  
Heat Diffusion ◽  
The Impact ◽  
Spatial Frequency Domain

In this paper we present a novel analytical approach for obtaining the thermal transfer function of multi-layer chips in the spatial frequency domain. The behavior of the transfer function is used to address a number of key issues such as 1) the appropriate power granularity required for microarchitecture thermal-power analysis, and 2) the impact of packaging and cooling solutions on heat removal from chip hotspots. The merit of the presented method is in 1) simplicity, such that even for rather complicated multi-layer structures the analysis takes only a fraction of a second, and 2) accuracy, because the approach is based on the exact solution of three-dimensional heat diffusion equations.

Three-Dimensional Tube Geometry Control for Rotary Draw Tube Bending, Part 1: Bend Angle and Overall Tube Geometry Control

2000 ◽  
Vol 123 (2) ◽  
pp. 258-265 ◽  
Author(s):  
Huazhou Lou ◽  
Kim A. Stelson
Keyword(s):  
Process Control ◽  
Control Strategy ◽  
Control Method ◽  
Three Dimensional ◽  
Bend Angle ◽  
Trial And Error ◽  
Operator Experience ◽  
Low Efficiency ◽  
Optimal Process Control ◽  
Tube Geometry

Traditional trial-and-error springback compensation methods have the problems of high scrap rate, low efficiency, high cost of fixtures and operator experience dependency. The method presented in this paper uses on-line measured springback data from the same batch to predict and compensate for springback. Because there are no springback data for the first bend, bend-rebend control is used to make the first bend to eliminate trial tubes. In addition to springback, relaxation and radial growth are also estimated and compensated for to make a bend more accurate. A process control method is developed to optimize the overall control strategy such that the overall tube error is minimized without increasing the required hardware accuracy. The optimal process control strategy has significantly higher accuracy than the traditional trial-and-error method. The details of statistical analysis of tube tolerance and adaptive bend correction algorithm are presented in Part 2 of the paper.

Research on trajectory planning of closed loop grouting robot

2021 ◽  
Vol 13 (11) ◽  
pp. 168781402110534
Author(s):  
Runmei Zhang ◽  
Rui Ren ◽  
Guan Luo ◽  
Shuai Li ◽  
Lijun Bi ◽  
...  
Keyword(s):  
Sliding Mode Control ◽  
Trajectory Planning ◽  
Closed Loop ◽  
High Efficiency ◽  
Control Method ◽  
Sliding Mode ◽  
Three Dimensional ◽  
Adaptive Sliding Mode Control ◽  
A Algorithm ◽  
Mode Control

In order to promote building intelligence and solve the disadvantages of traditional grouting technology, the trajectory planning of closed-loop grouting robot was designed. The minimumsnap optimization function was used to optimize the A* algorithm to realize the 2D trajectory planning, which could obtain a smooth, continuous route, and planning diagram of time distribution, speed, acceleration, and jerk. Further, the weight function of the improved A* algorithm was adjusted to perform 3D trajectory planning to reduce redundant nodes in the route. A new approaching law adaptive sliding mode control method was used to achieve precise trajectory tracking of the robotic arm and reduce the problem of chattering in sliding mode control. Through the design of closed-loop grouting robot and the research of trajectory planning, the two-dimensional and three-dimensional paths of grouting robot could be optimized. The system could realize automatic grouting operation. It could promote the development of high efficiency and safety in the construction grouting industry.

Cycle-to-Cycle Control of Multivariable Manufacturing Processes With Process Model Uncertainty

2004 ◽  
Author(s):  
Adam K. Rzepniewski ◽  
David E. Hardt ◽  
Chester D. Vaughan
Keyword(s):  
Process Control ◽  
Sheet Metal ◽  
Process Model ◽  
Closed Loop ◽  
Output Coupling ◽  
Manufacturing Processes ◽  
Input Multiple Output ◽  
Imperfect Knowledge ◽  
Single Input ◽  
Good Agreement

In-process closed-loop control of many manufacturing processes is often impractical owing to the impossibility or the prohibitively high cost of placing sensors and actuators necessary for in-process control. Such processes are usually left to statistical process control methods, which only identify problems without specifying solutions. Cycle-to-cycle control is a method for using feedback to improve product quality for processes that are inaccessible within a single processing cycle but can be changed between cycles. This type of control has the same objectives as run-by-run control. However, it is developed from a different point of view allowing easy analysis of the process’ transient closed-loop behavior due to changes in the target value or to output disturbances. Our previous work introduced cycle-to-cycle control for single input-single output processes and here it is extended to multiple input-multiple output processes. Gain selection, stability, and process variance amplification results are developed and compared with those obtained by previous researchers, showing good agreement. Then, the limitation of imperfect knowledge of the plant model is imposed. This is consistent with manufacturing environments that require minimal cost and number of tests in determining a valid process model. The effects of this limitation on system performance and stability are discussed. The theoretical results are applied to a novel, discrete-die sheet metal stretch-forming process. The classical, monolithic tool is replaced by a large number of small, separate pieces that can be reconfigured between cycles to approximate continuous shapes. Thus, each forming cycle can use a new input shape. The experimental system is an ideal candidate for the application of cycle-to-cycle control in a multivariable fashion. A linear process model is presented that includes the effects of single input-multiple output coupling. Experimental validation of variance amplification results for a sheet metal forming processes is presented with hundreds of inputs and outputs. While many controller designs could be considered a purely diagonal (decoupled) and a Linear Quadratic Regulator design are presented and discussed. Comparison between theory and experiments is provided, showing good agreement.

Base Algorithms of the Direct Adaptive Position-Path Control for Mobile Objects Positioning

2015 ◽  
Vol 763 ◽  
pp. 110-119 ◽  
Author(s):  
Viacheslav Pshikhopov ◽  
Mikhail Medvedev ◽  
Victor Krukhmalev ◽  
Victor Shevchenko
Keyword(s):  
Closed Loop ◽  
Control Method ◽  
Reference Model ◽  
Block Diagram ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Mobile Object ◽  
Mobile Objects ◽  
Closed Loop Systems ◽  
Path Control

Problem of a mobile object positioning in the presence of determinate disturbances is considered in this paper. A mobile object is described by kinematics and dynamics equations of a solid body in three dimensional space. The control inputs of the mobile object are forces and torques. Design of adaptive control is based on position-path control method for mobile objects. In this article two algorithms of the adaptive position-path control are developed. The first algorithm is adaptive position-path control with integration component and a reference model. The second algorithm is adaptive position-path control with a reference model and an extended mobile robot model. Block diagram of the direct adaptive position-path control system with a reference model is suggested. Design procedures of the adaptive position-path control systems and stability analysis of the closed-loop systems are presented. Computer simulation results of the designed adaptive closed-loop systems with both constant and variable disturbances are presented. On base of the analysis and modeling results conclusions are provided.

The Site Visualization and Closed-Loop Control for 3D Assembly Process

2014 ◽  
Vol 621 ◽  
pp. 617-626
Author(s):  
Peng Zhang ◽  
Jin Song Bao ◽  
Zhi Bo Yang ◽  
Feng Chun Huang
Keyword(s):  
Closed Loop ◽  
Control Method ◽  
Rapid Development ◽  
Three Dimensional ◽  
Design Stage ◽  
Closed Loop Control ◽  
Assembly Process ◽  
Process Technology ◽  
Loop Control ◽  
3D Assembly

With the rapid development of 3D CAD technology, 3D assembly process is playing an important role in the on-site assembly. A closed-loop control method and three-dimensional site visualization technology site is presented. The methodology takes into account CAD design stage, assembly process design, site assembly and site inspection. The method includes three key technologies: the verification process technology of three-dimensional assembly process, optimization and process simulation techniques of site assembly, closed-loop control technology of assembly process quality inspection. Finally, the method and technology has applied in the actual assembly, and achieved good results.

Three-Dimensional Tube Geometry Control for Rotary Draw Tube Bending: Part 1—Bend Angle and Overall Tube Geometry Control

2000 ◽  
Author(s):  
Huazhou Lou ◽  
Kim A. Stelson
Keyword(s):  
Process Control ◽  
Control Strategy ◽  
Control Method ◽  
Three Dimensional ◽  
Bend Angle ◽  
Trial And Error ◽  
Operator Experience ◽  
Low Efficiency ◽  
Optimal Process Control ◽  
Tube Geometry

Abstract Traditional trial-and-error springback compensation methods have the problems of high scrap rate, low efficiency, high cost of fixtures and operator experience dependency. The method presented in this paper uses on-line measured springback data from the same batch to predict and compensate for springback. Because there are no springback data for the first bend, bend-rebend control is used to make the first bend to eliminate trial tubes. In addition to springback, relaxation and radial growth are also estimated and compensated for to make a bend more accurate. A process control method is developed to optimize the overall control strategy such that the overall tube error is minimized without increasing the required hardware accuracy. The optimal process control strategy has significantly higher accuracy than the traditional trial-and-error method. The details of statistical analysis of tube tolerance and adaptive bend correction algorithm are presented in part 2 of the paper.

Disorganization of a hole tone feedback loop by an axisymmetric obstacle on a downstream end plate

2014 ◽  
Vol 757 ◽  
pp. 908-942 ◽  
Author(s):  
K. Matsuura ◽  
M. Nakano
Keyword(s):  
Nozzle Exit ◽  
Passive Control ◽  
Control Method ◽  
Three Dimensional ◽  
Acoustic Power ◽  
Shear Layers ◽  
Mean Velocity ◽  
End Plate ◽  
Air Jet ◽  
Practical Engineering

AbstractThis study investigates the suppression of the sound produced when a jet, issued from a circular nozzle or hole in a plate, goes through a similar hole in a second plate. The sound, known as a hole tone, is encountered in many practical engineering situations. The mean velocity of the air jet $\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}u_0$ was $6\text {--}12\ \mathrm{m}\ {\mathrm{s}}^{-1}$. The nozzle and the end plate hole both had a diameter of 51 mm, and the impingement length $L_{im}$ between the nozzle and the end plate was 50–90 mm. We propose a novel passive control method of suppressing the tone with an axisymmetric obstacle on the end plate. We find that the effect of the obstacle is well described by the combination ($W/L_{im}$, $h$) where $W$ is the distance from the edge of the end plate hole to the inner wall of the obstacle, and $h$ is the obstacle height. The tone is suppressed when backflows from the obstacle affect the jet shear layers near the nozzle exit. We do a direct sound computation for a typical case where the tone is successfully suppressed. Axisymmetric uniformity observed in the uncontrolled case is broken almost completely in the controlled case. The destruction is maintained by the process in which three-dimensional vortices in the jet shear layers convect downstream, interact with the obstacle and recursively disturb the jet flow from the nozzle exit. While regions near the edge of the end plate hole are responsible for producing the sound in the controlled case as well as in the uncontrolled case, acoustic power in the controlled case is much lower than in the uncontrolled case because of the disorganized state.

Sign in / Sign up

Export Citation Format

Share Document