Stabilization of Filament Production Rate for Screw Extrusion-Based Polymer Three-Dimensional-Printing

2019 ◽  
Vol 142 (3) ◽  
Author(s):  
Shumon Koga ◽  
David Straub ◽  
Mamadou Diagne ◽  
Miroslav Krstic
Keyword(s):  
Differential Equation ◽  
3D Printing ◽  
Temperature Profile ◽  
Time Evolution ◽  
Output Feedback ◽  
Three Dimensional ◽  
Output Feedback Control ◽  
Raw Material ◽  
Interface Position ◽  
Screw Extrusion

Abstract Polymer three-dimensional (3D)-printing has been commercialized rapidly during recent years; however, there remains a matter of improving the manufacturing speed. Screw extrusion has a strong potential to fasten the process through the simultaneous operation of the filament production and the deposition. This paper develops a control algorithm for screw extrusion-based 3D printing of thermoplastic materials through an observer-based output feedback design. We consider the thermodynamic model describing the time evolution of the temperature profile of an extruded polymer by means of a partial differential equation (PDE) defined on the time-varying domain. The time evolution of the spatial domain is governed by an ordinary differential equation that reflects the dynamics of the position of the phase change interface between polymer granules and molten polymer deposited as a molten filament. The steady-state profile of the distributed temperature along the extruder is obtained when the desired setpoint for the interface position is prescribed. To enhance the feasibility of our previous design, we develop a PDE observer to estimate the temperature profile via measured values of surface temperature and the interface position. An output feedback control law considering a cooling mechanism at the boundary inlet as an actuator is proposed. In extruders, the control of raw material temperature is commonly achieved using preconditioners as part of the inlet feeding mechanism. For some given screw speeds that correspond to slow and fast operating modes, numerical simulations are conducted to prove the performance of the proposed controller. The convergence of the interface position to the desired setpoint is achieved under physically reasonable temperature profiles.

Observer-based output feedback control design for a coupled system of fractional ordinary and reaction–diffusion equations

2020 ◽  
Author(s):  
Shadi Amiri ◽  
Mohammad Keyanpour ◽  
Asadollah Asaraii
Keyword(s):  
Differential Equation ◽  
Output Feedback ◽  
Closed Loop ◽  
Output Feedback Control ◽  
Reaction Diffusion ◽  
Coupled System ◽  
Reaction Diffusion Equations ◽  
Backstepping Method ◽  
Neumann Type ◽  
Fractional Reaction

Abstract In this paper, we investigate the stabilization problem of a cascade of a fractional ordinary differential equation (FODE) and a fractional reaction–diffusion (FRD) equation where the interconnections are of Neumann type. We exploit the partial differential equation backstepping method for designing a controller, which guarantees the Mittag–Leffler stability of the FODE-FRD cascade. Moreover, we propose an observer that is Mittag–Leffler convergent. Also, we propose an output feedback boundary controller, and we prove that the closed-loop FODE-FRD system is Mittag–Leffler stable in the sense of the corresponding norm. Finally, numerical simulations are presented to verify the results.

scholarly journals 3D Printed In Vitro Dentin Model to Investigate Occlusive Agents against Tooth Sensitivity

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7255
Author(s):  
Shiva Naseri ◽  
Megan E. Cooke ◽  
Derek H. Rosenzweig ◽  
Maryam Tabrizian
Keyword(s):  
3D Printing ◽  
Type I Collagen ◽  
Three Dimensional ◽  
Raw Material ◽  
Type I ◽  
Dentinal Tubule ◽  
Human Teeth ◽  
Tooth Sensitivity ◽  
3D Printed

Tooth sensitivity is a painful and very common problem. Often stimulated by consuming hot, cold, sweet, or acidic foods, it is associated with exposed dentin microtubules that are open to dental pulp. One common treatment for tooth hypersensitivity is the application of occlusive particles to block dentin microtubules. The primary methodology currently used to test the penetration and occlusion of particles into dentin pores relies upon dentin discs cut from extracted bovine/human teeth. However, this method is limited due to low accessibility to the raw material. Thus, there is a need for an in vitro dentin model to characterize the effectiveness of occlusive agents. Three-dimensional printing technologies have emerged that make the printing of dentin-like structures possible. This study sought to develop and print a biomaterial ink that mimicked the natural composition and structure of dentin tubules. A formulation of type I collagen (Col), nanocrystalline hydroxyapatite (HAp), and alginate (Alg) was found to be suitable for the 3D printing of scaffolds. The performance of the 3D printed dentin model was compared to the natural dentin disk by image analysis via scanning electron microscopy (SEM), both pre- and post-treatment with occlusive microparticles, to evaluate the degree of dentinal tubule occlusion. The cytocompatibility of printed scaffolds was also confirmed in vitro. This is a promising biomaterial system for the 3D printing of dentin mimics.

Modified Sky-Hook Control of a Semi-Active Suspension System Using H∞ Robust Control Theory

2009 ◽  
Author(s):  
Mohammad Saber Fallah ◽  
Rama Bhat ◽  
Wen-Fang Xie
Keyword(s):  
Feedback Control ◽  
Output Feedback ◽  
Controller Design ◽  
Kinematic Model ◽  
Three Dimensional ◽  
Output Feedback Control ◽  
Suspension System ◽  
Linear Matrix ◽  
Control Force ◽  
The Stability

The main focus of the present paper is on the design of a modified sky-hook control of a semi-active Macpherson suspension system by means of H∞ Output Feedback Control (OFC) theory. To this end, a new dynamic model, incorporating the kinematics of the suspension system, is used for the controller design. The combination of a Linear Matrix Inequality (LMI) solver and Genetic Algorithm (GA) is adopted to regulate the static output feedback control gain so that the stability conditions are fulfilled and control objectives are achieved. Meanwhile, a three-dimensional kinematic model of the system is incorporated to investigate the influence of the control force variation on the steering, handling and stability of the vehicle. A geometric relation of the vehicle roll center is employed to study one more extra aspect of the comfort and stability of the vehicle. The results show that the proposed controller improves the kinematic and dynamic performances of the suspension well compared with those of the passive system. Moreover, it is concluded that a superior stability of the vehicle during the cornering can be achieved by adjusting the height of the vehicle roll center passively so that the stability of the vehicle is improved while the forward motion specifications can be modified by an appropriate suspension control design.

scholarly journals Nonlinear-Observer-Based Design Approach for Adaptive Event-Driven Tracking of Uncertain Underactuated Underwater Vehicles

Mathematics ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 1144
Author(s):  
Jin Hoe Kim ◽  
Sung Jin Yoo
Keyword(s):  
Output Feedback ◽  
Degrees Of Freedom ◽  
Dimensional Space ◽  
Error Function ◽  
Tracking Error ◽  
Three Dimensional ◽  
Output Feedback Control ◽  
Underwater Vehicles ◽  
Nonlinear Observer ◽  
Event Driven

A nonlinear-observer-based design methodology is proposed for an adaptive event-driven output-feedback tracking problem with guaranteed performance of uncertain underactuated underwater vehicles (UUVs) in six-degrees-of-freedom (6-DOF). A nonlinear observer using adaptive neural networks is presented to estimate the velocity information in the presence of unknown nonlinearities in the dynamics of 6-DOF UUVs where a state transformation approach using a time-varying scaling factor is introduced. Then, an output-feedback tracker using a nonlinear error function and estimated states is recursively designed to overcome the underactuated problem of the system dynamics and to guarantee preselected control performance in three-dimensional space. It is shown that the tracking error of the nonlinear-observer-based output-feedback control system exponentially converges a small neighbourhood around the zero. Efficiency of the resulting output-feedback strategy is verified through a simulation.

scholarly journals Extrusion-Based 3D Printing Applications of PLA Composites: A Review

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 390
Author(s):  
Eda Hazal Tümer ◽  
Husnu Yildirim Erbil
Keyword(s):  
3D Printing ◽  
Bone Repair ◽  
Fused Deposition Modeling ◽  
Water Solubility ◽  
Raw Materials ◽  
Three Dimensional ◽  
Cost Effective ◽  
Raw Material ◽  
Preparation Methods ◽  
Fused Deposition

Polylactic acid (PLA) is the most widely used raw material in extrusion-based three-dimensional (3D) printing (fused deposition modeling, FDM approach) in many areas since it is biodegradable and environmentally friendly, however its utilization is limited due to some of its disadvantages such as mechanical weakness, water solubility rate, etc. FDM is a simple and more cost-effective fabrication process compared to other 3D printing techniques. Unfortunately, there are deficiencies of the FDM approach, such as mechanical weakness of the FDM parts compared to the parts produced by the conventional injection and compression molding methods. Preparation of PLA composites with suitable additives is the most useful technique to improve the properties of the 3D-printed PLA parts obtained by the FDM method. In the last decade, newly developed PLA composites find large usage areas both in academic and industrial circles. This review focuses on the chemistry and properties of pure PLA and also the preparation methods of the PLA composites which will be used as a raw material in 3D printers. The main drawbacks of the pure PLA filaments and the necessity for the preparation of PLA composites which will be employed in the FDM-based 3D printing applications is also discussed in the first part. The current methods to obtain PLA composites as raw materials to be used as filaments in the extrusion-based 3D printing are given in the second part. The applications of the novel PLA composites by utilizing the FDM-based 3D printing technology in the fields of biomedical, tissue engineering, human bone repair, antibacterial, bioprinting, electrical conductivity, electromagnetic, sensor, battery, automotive, aviation, four-dimensional (4D) printing, smart textile, environmental, and luminescence applications are presented and critically discussed in the third part of this review.

Output feedback averaged sub-gradient integral sliding mode control to regulate the tridimensional autonomous motion of autonomous submersible vehicles

2021 ◽  
pp. 095965182110564
Author(s):  
Alejandra Hernández-Sánchez ◽  
Alexander Poznyak ◽  
Olga Andrianova ◽  
Isaac Chairez
Keyword(s):  
Output Feedback ◽  
Sliding Mode ◽  
Center Of Mass ◽  
Tracking Error ◽  
Three Dimensional ◽  
Output Feedback Control ◽  
Extremum Seeking ◽  
Integral Sliding Mode ◽  
Twisting Algorithm ◽  
Reference Trajectories

This study presents the development of an output feedback control for regulating the movement of an autonomous submersible vehicles in the tridimensional space. The controller formulation applies the Averaged Sub-Gradient Integral Sliding Mode which is fed with the estimation of the translational velocity states by a distributed super-twisting algorithm. The structure of the autonomous submersible vehicles dynamics permits the implementation of the ASG algorithm using the estimates of translation velocity. The proposed scheme solves a non-linear extremum seeking problem that aims to minimize a non-strictly convex function that depends on the tracking error defined by the difference of some suitable reference trajectories and the coordinates of the submarine center of mass. The desired reference trajectories were designed to force the autonomous submersible vehicles three-dimensional motion to a continuous circuit in an oscillating shape over the horizontal plane combined with a submersion on the z-axis. The comparison between the proposed controller, the ASG with complete knowledge of the states and the state feedback controller is presented. This comparison confirms the output feedback ASG controller forced the autonomous submersible vehicles to the desired trajectory with a notable difference in the magnitude of the control given the estimation of the states. These outcomes justify the potential contributions of the suggested ASG integrated with the super-twisting algorithm to obtain the local minimization of the evaluated functional depending on the tracking error. The results justify the potential contributions of the suggested ASG with the super-twisting algorithm to regulate the position of the autonomous submersible vehicles to the desired trajectory.

scholarly journals Fabrication of Biocompatible Polycaprolactone–Hydroxyapatite Composite Filaments for the FDM 3D Printing of Bone Scaffolds

2021 ◽  
Vol 11 (14) ◽  
pp. 6351
Author(s):  
Chang Geun Kim ◽  
Kyung Seok Han ◽  
Sol Lee ◽  
Min Cheol Kim ◽  
Soo Young Kim ◽  
...  
Keyword(s):  
3D Printing ◽  
Fused Deposition Modeling ◽  
Bone Structure ◽  
Three Dimensional ◽  
Tensile Tests ◽  
Raw Material ◽  
Fused Deposition ◽  
Bone Scaffolds ◽  
3D Printed ◽  
Mechanical Tensile

Recently, three-dimensional printing (3DP) technology has been widely adopted in biology and biomedical applications, thanks to its capacity to readily construct complex 3D features. Using hot-melt extrusion 3DP, scaffolds for bone tissue engineering were fabricated using a composite of biodegradable polycaprolactone (PCL) and hydroxyapatite (HA). However, there are hardly any published reports on the application of the fused deposition modeling (FDM) method using feed filaments, which is the most common 3D printing method. In this study, we report on the fabrication and characterization of biocompatible filaments made of polycaprolactone (PCL)/hydroxyapatite (HA), a raw material mainly used for bone scaffolds, using FDM 3D printing. A series of filaments with varying HA content, from 5 to 25 wt.%, were fabricated. The mechanical and electrical properties of the various structures, printed using a commercially available 3D printer, were examined. Specifically, mechanical tensile tests were performed on the 3D-printed filaments and specimens. In addition, the electrical dielectric properties of the 3D-printed structures were investigated. Our method facilitates the fabrication of biocompatible structures using FDM-type 3DP, creating not only bone scaffolds but also testbeds for mimicking bone structure that may be useful in various fields of study.

Axial Vibration Suppression in a Partial Differential Equation Model of Ascending Mining Cable Elevator

2018 ◽  
Vol 140 (11) ◽  
Author(s):  
Ji Wang ◽  
Shumon Koga ◽  
Yangjun Pi ◽  
Miroslav Krstic
Keyword(s):  
Differential Equation ◽  
Partial Differential Equation ◽  
Feedback Control ◽  
Output Feedback ◽  
Vibration Suppression ◽  
Output Feedback Control ◽  
Control Law ◽  
Axial Vibration ◽  
Hydraulic Actuator ◽  
Partial Differential

Lifting up a cage with miners via a mining cable causes axial vibrations of the cable. These vibration dynamics can be described by a coupled wave partial differential equation-ordinary differential equation (PDE-ODE) system with a Neumann interconnection on a time-varying spatial domain. Such a system is actuated not at the moving cage boundary, but at a separate fixed boundary where a hydraulic actuator acts on a floating sheave. In this paper, an observer-based output-feedback control law for the suppression of the axial vibration in the varying-length mining cable is designed by the backstepping method. The control law is obtained through the estimated distributed vibration displacements constructed via available boundary measurements. The exponential stability of the closed-loop system with the output-feedback control law is shown by Lyapunov analysis. The performance of the proposed controller is investigated via numerical simulation, which illustrates the effective vibration suppression with the fast convergence of the observer error.

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