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.

Voltage-Mode Multifunctional Biquadratic Filter Using VDDDA

2015 ◽  
Vol 781 ◽  
pp. 155-159 ◽  
Author(s):  
Suriya Soisang ◽  
Kamon Jirasereemomkul ◽  
Winai Jaikla ◽  
Kohji Higuchi
Keyword(s):  
Quality Factors ◽  
Active Device ◽  
Voltage Mode ◽  
Input Multiple Output ◽  
Low Pass ◽  
Single Structure ◽  
Biquadratic Filter ◽  
Single Input ◽  
Band Pass ◽  
Good Agreement

This paper presents a new voltage-mode single-input multiple-output multifunctional biquadratic filter using voltage differencing differential difference amplifiers (VDDDA) with high-input impedance. It consists of two VDDDA, two resistors, and two grounded capacitors. It can synthesize basic filter functions: high-past (HP), low-pass (LP) and band-pass (BP), responding through only single structure. The natural frequency can obtain by adjusting bias currents of VDDDA without disturbing quality factors. Because of using VDDDA as an active device in the circuit, the power consumption was low. The simulation using PSPICE program indicated that circuit operation has good agreement with the theory.

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.

SAMPL6 Challenge Results from pKa Predictions Based on a General Gaussian Process Model

2018 ◽  
Author(s):  
Caitlin C. Bannan ◽  
David Mobley ◽  
A. Geoff Skillman
Keyword(s):  
Gaussian Process ◽  
Process Model ◽  
Molecular Graph ◽  
Gaussian Process Regression ◽  
Ionization State ◽  
Training Set ◽  
Physiochemical Properties ◽  
Quantile Plots ◽  
Physical And Chemical ◽  
Good Agreement

<div>A variety of fields would benefit from accurate pK<sub>a</sub> predictions, especially drug design due to the affect a change in ionization state can have on a molecules physiochemical properties.</div><div>Participants in the recent SAMPL6 blind challenge were asked to submit predictions for microscopic and macroscopic pK<sub>a</sub>s of 24 drug like small molecules.</div><div>We recently built a general model for predicting pK<sub>a</sub>s using a Gaussian process regression trained using physical and chemical features of each ionizable group.</div><div>Our pipeline takes a molecular graph and uses the OpenEye Toolkits to calculate features describing the removal of a proton.</div><div>These features are fed into a Scikit-learn Gaussian process to predict microscopic pK<sub>a</sub>s which are then used to analytically determine macroscopic pK<sub>a</sub>s.</div><div>Our Gaussian process is trained on a set of 2,700 macroscopic pK<sub>a</sub>s from monoprotic and select diprotic molecules.</div><div>Here, we share our results for microscopic and macroscopic predictions in the SAMPL6 challenge.</div><div>Overall, we ranked in the middle of the pack compared to other participants, but our fairly good agreement with experiment is still promising considering the challenge molecules are chemically diverse and often polyprotic while our training set is predominately monoprotic.</div><div>Of particular importance to us when building this model was to include an uncertainty estimate based on the chemistry of the molecule that would reflect the likely accuracy of our prediction. </div><div>Our model reports large uncertainties for the molecules that appear to have chemistry outside our domain of applicability, along with good agreement in quantile-quantile plots, indicating it can predict its own accuracy.</div><div>The challenge highlighted a variety of means to improve our model, including adding more polyprotic molecules to our training set and more carefully considering what functional groups we do or do not identify as ionizable. </div>

scholarly journals Compensated Single Input Multiple Output Flyback Converter

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3009
Author(s):  
Mohammad Tahan ◽  
David O. Bamgboje ◽  
Tingshu Hu
Keyword(s):  
Transient Response ◽  
Current Mode ◽  
Voltage Regulation ◽  
Buck Converter ◽  
Output Channel ◽  
Flyback Converter ◽  
Input Multiple Output ◽  
Voltage Deviation ◽  
Single Input ◽  
The Cross

A new single-input multiple-output (SIMO) converter is proposed in this work by incorporating flyback and buck converters in a master–slave configuration. The objective of this work is to address the cross regulation problem, achieve tight voltage regulation, improve the circuit form factor and attain a fast transient response for a SIMO flyback converter. The flyback converter maintains the output channels within 10% of their rated voltages and the SIMO buck converter is placed in series with the flyback converter such that it compensates for the output voltage deviation. Moreover, a time multiplexing switching scheme decouples output channel to eliminate the cross-regulation problem and remove the need for an additional winding transformer per each output channel. A type II compensator with a peak current mode controller was designed to achieve faster transient response which is critical for the proposed configuration. A thorough steady-state analysis was carried out on a triple output channel topology to obtain the design criteria and component values. MATLAB/Simscape modelling and simulation was used to validate the effectiveness of the proposed converter with the result yielding satisfactory transience even with load disturbance. Additionally, the result of the proposed converter is compared with previously published works.

scholarly journals Measurement and Process Control in Precision Hot Embossing

2013 ◽  
Author(s):  
Maia R. Bageant ◽  
David E. Hardt
Keyword(s):  
Process Control ◽  
Material Properties ◽  
Disturbance Rejection ◽  
Closed Loop ◽  
Hot Embossing ◽  
Commercial Production ◽  
Bulk Deformation ◽  
Functional Tests ◽  
Medical Field ◽  
High Degree

Microfluidic technologies hold a great deal of promise in advancing the medical field, but transitioning them from research to commercial production has proven problematic. We propose precision hot embossing as a process to produce high volumes of devices with low capital cost and a high degree of flexibility. Hot embossing has not been widely applied to precision forming of hard polymers at viable production rates. To this end we have developed experimental equipment capable of maintaining the necessary precision in forming parameters while minimizing cycle time. In addition, since equipment precision alone does not guarantee consistent product quality, our work also focuses on real-time sensing and diagnosis of the process. This paper covers both the basic details for a novel embossing machine, and the utilization of the force and displacement data acquired during the embossing cycle to diagnose the state of the material and process. The precision necessary in both the forming machine and the instrumentation will be covered in detail. It will be shown that variation in the material properties (e.g. thickness, glass transition temperature) as well as the degree of bulk deformation of the substrate can be detected from these measurements. If these data are correlated with subsequent downstream functional tests, a total measure of quality may be determined and used to apply closed-loop cycle-to-cycle control to the entire process. By incorporating automation and specialized precision equipment into a tabletop “microfactory” setting, we aim to demonstrate a high degree of process control and disturbance rejection for the process of hot embossing as applied at the micron scale.

Robot Assisted Modal Analysis on a Stationary Bladed Wheel

2014 ◽  
Author(s):  
L. Bertini ◽  
B. Monelli ◽  
P. Neri ◽  
C. Santus ◽  
A. Guglielmo
Keyword(s):  
Three Dimensional ◽  
Laser Doppler Vibrometer ◽  
Testing Time ◽  
Real Representation ◽  
The Real ◽  
Complex Formulation ◽  
Frequency Matching ◽  
Input Multiple Output ◽  
Multiple Measurements ◽  
Single Input

This paper shows an automated procedure to experimentally find the eigenmodes of a bladed wheel with highly three-dimensional geometry. The stationary wheel is supported in free-free conditions, neglecting stress-stiffening effects. The single input / multiple output approach was followed. The vibration speed was measured by means of a laser-Doppler vibrometer, and an anthropomorphic robot was used for accurate orientation and positioning of the measuring laser beam, allowing multiple measurements during a limited testing time. The vibration at corresponding points on each blade was measured and the data elaborated in order to find the initial (lower frequency) modes. These modal shapes were then compared to finite element simulations and accurate frequency matching and exact number of nodal diameters obtained. Being the modes cyclically harmonic, the complex formulation could be attractive, being not affected by the angular phase of the mode representation. Nevertheless, stationary modes were experimentally detected, rather than rotating, and then the real representation was necessary. The discrete Fourier transform of the blade displacements easily allowed to find both the angular phase and the correct number of nodal diameters. Successful MAC experimental to analytical comparison was finally obtained with the real representation after introducing the proper angular phase for each mode.

The Ship Track Keeping With Roll Reduction Using a Multiple-States PD Controller on the Rudder Operation

2008 ◽  
Vol 45 (01) ◽  
pp. 21-27
Author(s):  
Ming-Chung Fang ◽  
Jhih-Hong Luo
Keyword(s):  
Numerical Model ◽  
Line Of Sight ◽  
Pd Controller ◽  
Input Multiple Output ◽  
Maneuvering In Waves ◽  
Single Input ◽  
Reduction Function ◽  
Simulation Results ◽  
Guidance Technique ◽  
Present Simulation

The paper presents a nonlinear hydrodynamic numerical model with multiple-states proportional-derivative (PD) controllers for simulating the ship's tracking in random sea. By way of the rudder operation, the track-keeping ability of the PD controller on the ship is examined using the line-of-sight (LOS) guidance technique. Furthermore, the roll-reduction function using the rudder control is also included in the PD controller. From the present simulation results, the single-input multiple-output (SIMO) heading/roll PD controller including LOS technique developed here indeed works, either for the roll reduction or for track keeping while the ship is maneuvering in waves.

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