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Mechanical and Aerospace Engineering Faculty Research & Creative Works
- Keyword
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- Optimal Control (5)
- Force Control (3)
- Machining Force Control (3)
- Position Control (3)
- Process Control (3)
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- Servomechanisms (3)
- Contour Control (2)
- Hierarchical Optimal Force-Position-Contour Control (2)
- Hierarchical Systems (2)
- Machine Tool Servomechanism Control (2)
- Machine Tools (2)
- Machining (2)
- Machining Process Control (2)
- Reference Servomechanism Position Tracking (2)
- Actuators (1)
- Adhesion (1)
- Aggregation (1)
- Aircraft Control (1)
- Aircrafts (1)
- Approximate-Then-Design (1)
- Brownian Motion (1)
- Closed loop systems (1)
- Cohesive zone (1)
- Computational Design Methods (1)
- Control Theory (1)
- Controller Design (1)
- Cooperative Formation Flying (1)
- Design Knowledge Representation (1)
- Design-Then-Approximate (1)
- Discrete Actuators (1)
Articles 1 - 19 of 19
Full-Text Articles in Engineering
A Qualitative Modeling Method For Platform Design, Michael Van Wie, Robert B. Stone, Asli Sahin, Janis Terpenny, Fabrice Alizon, Steve Shooter, Timothy Simpson
A Qualitative Modeling Method For Platform Design, Michael Van Wie, Robert B. Stone, Asli Sahin, Janis Terpenny, Fabrice Alizon, Steve Shooter, Timothy Simpson
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The development of a collection of related products sharing a common platform represents an important approach in modern product design. an ongoing problem is the application of design methods toward a limited set of evolving product data and archived design knowledge to search and explore alternative platform options. with the goal of maximizing the reuse of end item artifacts and supply chain elements, we propose a design modeling method using basic qualitative relationships among relevant performance, design, and noise parameters in the system of interest. by using qualitative models related to multiple levels of design data, the method provides a …
Repeatable Nanostructures In Dielectrics By Femtosecond Laser Pulse Trains, Lan Jiang, Hai-Lung Tsai
Repeatable Nanostructures In Dielectrics By Femtosecond Laser Pulse Trains, Lan Jiang, Hai-Lung Tsai
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Using the plasma model recent developed by the authors, this study predicts the existence of a constant ablation-depth zone with respect to fluence in femtosecond laser ablation of dielectrics, which has also been observed experimentally. It is found that the value of the constant ablation depth is significantly decreased by the pulse train technology. Repeatable nanostructures can be achieved with the parameters in the constant ablation-depth zone of a femtosecond pulse train, even when the laser system is subject to fluctuations in fluences.
Special Issue: Engineering Applications Of Representations Of Function, Part 2, Robert B. Stone, Amaresh Chakrabarti
Special Issue: Engineering Applications Of Representations Of Function, Part 2, Robert B. Stone, Amaresh Chakrabarti
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Three-Dimensional Radiative Transfer In An Isotropically Scattering, Plane-Parallel Medium: Generalized X- And Y-Functions, D. W. Mueller, A. L. Crosbie
Three-Dimensional Radiative Transfer In An Isotropically Scattering, Plane-Parallel Medium: Generalized X- And Y-Functions, D. W. Mueller, A. L. Crosbie
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The topic of this work is the generalized X- and Y-functions of multidimensional radiative transfer. the physical problem considered is spatially varying, collimated radiation incident on the upper boundary of an isotropically scattering, plane-parallel medium. an integral transform is used to reduce the three-dimensional transport equation to a one-dimensional form, and a modified Ambarzumian's method is used to derive coupled, integro-differential equations for the source functions at the boundaries of the medium. the resulting equations are said to be in double-integral form because the integration is over both angular variables. Numerical results are presented to illustrate the computational characteristics of …
Hierarchical Optimal Force-Position-Contour Control Of Machining Processes. Part Ii. Illustrative Example, Yan Tang, Robert G. Landers, S. N. Balakrishnan
Hierarchical Optimal Force-Position-Contour Control Of Machining Processes. Part Ii. Illustrative Example, Yan Tang, Robert G. Landers, S. N. Balakrishnan
Mechanical and Aerospace Engineering Faculty Research & Creative Works
There has been a tremendous amount of research in machine tool servomechanism control, contour control, and machining force control; however, to date these technologies have not been tightly integrated. This paper develops a hierarchical optimal control methodology for the simultaneous regulation of servomechanism positions, contour error, and machining forces. The contour error and machining force process reside in the top level of the hierarchy where the goals are to 1) drive the contour error to zero to maximize quality and 2) maintain a constant cutting force to maximize productivity. These goals are systematically propagated to the bottom level, via aggregation …
Hierarchical Optimal Force-Position-Contour Control Of Machining Processes. Part I. Controller Methodology, Yan Tang, Robert G. Landers, S. N. Balakrishnan
Hierarchical Optimal Force-Position-Contour Control Of Machining Processes. Part I. Controller Methodology, Yan Tang, Robert G. Landers, S. N. Balakrishnan
Mechanical and Aerospace Engineering Faculty Research & Creative Works
There has been a tremendous amount of research in machine tool servomechanism control, contour control, and machining force control; however, to date these technologies have not been tightly integrated. This paper develops a hierarchical optimal control methodology for the simultaneous regulation of servomechanism positions, contour error, and machining forces. The contour error and machining force process reside in the top level of the hierarchy where the goals are to 1) drive the contour error to zero to maximize quality and 2) maintain a constant cutting force to maximize productivity. These goals are systematically propagated to the bottom level, via aggregation …
The Coupling Effect Of Interfacial Adhesion And Tensile Residual Stress On A Thin Membrane Adhered To A Flat Punch, Kai Tak Wan, Lior Kogut
The Coupling Effect Of Interfacial Adhesion And Tensile Residual Stress On A Thin Membrane Adhered To A Flat Punch, Kai Tak Wan, Lior Kogut
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Adhesion and residual stress play a critical role in the performance and reliability of microdevices, in particular, the cross bridge of RF microswitches. to investigate their combinatorial influences on thin films, an elastic model is constructed for a clamped circular membrane in contact with the planar surface of a rigid cylindrical punch. External force applied to the punch leads to thin film delamination and ultimately 'pull-off' at a critical non-zero contact radius. Characteristic trends of the mechanical responses were obtained for fixed load and fixed grips in terms of pull-off force, punch displacement and contact radius. It is shown that …
A Systematic Method For Characterizing The Elastic Properties And Adhesion Of A Thin Polymer Membrane, Bing Feng Ju, Yang Ju, Masumi Saka, Kuo Kang Liu, Kai Tak Wan
A Systematic Method For Characterizing The Elastic Properties And Adhesion Of A Thin Polymer Membrane, Bing Feng Ju, Yang Ju, Masumi Saka, Kuo Kang Liu, Kai Tak Wan
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The elastic properties and adhesion of a thin silicone rubber membrane have been characterized. an effective instrumentation embodying a video-enhanced microscope, which meets force and displacement resolution of 0.1μN and 10 nm, was developed. It provides the capability of simultaneously measuring both the applied force and the resultant displacement of the thin polymer membrane. a linear theoretical elastic solution was applied to quantitatively interpret the measured central deflection of the membrane under a circular concentrical load. Young's modulus of the membrane can be easily determined once the applied force and the central deflection, together with the essential dimensions, are known. …
Hierarchical Optimal Force-Position Control Of A Turning Process, B. Pandurangan, Robert G. Landers, S. N. Balakrishnan
Hierarchical Optimal Force-Position Control Of A Turning Process, B. Pandurangan, Robert G. Landers, S. N. Balakrishnan
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Machining process control technologies are currently not well integrated into machine tool controllers and, thus, servomechanism dynamics are often ignored when designing and implementing process controllers. In this brief, a hierarchical controller is developed that simultaneously regulates the servomechanism motions and cutting forces in a turning operation. The force process and servomechanism system are separated into high and low levels, respectively, in the hierarchy. The high-level goal is to maintain a constant cutting force to maximize productivity while not violating a spindle power constraint. This goal is systematically propagated to the lower level and combined with the low-level goal to …
Multiple Spacecraft Formation Control Using Θ - D Method, Ming Xin, S. N. Balakrishnan, Henry J. Pernicka
Multiple Spacecraft Formation Control Using Θ - D Method, Ming Xin, S. N. Balakrishnan, Henry J. Pernicka
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Multiple spacecraft formation control about the L2 libration point is investigated in this paper. the circular restricted three-body problem with Sun and Earth as the two primaries is utilized as a framework of study. the idea of virtual structure is considered as the architecture of multiple spacecraft formation. the center of the virtual rigid body follows a nominal orbit around the L2 libration point. the individual spacecraft is controlled so as to keep a constant relative distance from the center of the virtual structure. a nonlinear model is developed that describes the relative formation dynamics. This nonlinear control problem was …
Measurement And Control Of Torque Ripple-Induced Frame Torsional Vibration In A Surface Mount Permanent Magnet Machine, Jason Neely, Steven Pekarek, Daniel S. Stutts, Philip Beccue
Measurement And Control Of Torque Ripple-Induced Frame Torsional Vibration In A Surface Mount Permanent Magnet Machine, Jason Neely, Steven Pekarek, Daniel S. Stutts, Philip Beccue
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A sensor to measure the stator torsional vibration due to torque ripple produced by a surface mount permanent magnet machine is first described. The sensor is relatively inexpensive and is straight forward to incorporate into a drive system. Experiments are performed to validate that the voltage produced by the sensor is linearly related to torque ripple amplitude. Closed-loop controllers are then described that adjust the stator current harmonics applied to the machine to achieve a commanded average torque while mitigating measured torsional vibration. Simulation and experimental results are used to demonstrate the effectiveness of the control techniques.
Dynamic Re-Optimization Of A Mems Controller In Presence Of Unmodeled Uncertainties, Nishant Unnikrishnan, S. N. Balakrishnan, Venkat Durbha
Dynamic Re-Optimization Of A Mems Controller In Presence Of Unmodeled Uncertainties, Nishant Unnikrishnan, S. N. Balakrishnan, Venkat Durbha
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Online trained neural networks have become popular in recent years in designing robust and adaptive controllers for dynamic systems with uncertainties in their system equations because of their universal function approximation property. This paper discusses a technique that dynamically reoptimizes a Single Network Adaptive Critic (SNAC) based optimal controller in the presence of unmodeled uncertainties. The controller design is carried out in two steps: (i) synthesis of a set of online neural networks that capture the uncertainties in the plant equations on-line (ii) re-optimization of the existing optimal controller to drive the states of the plant to a desired reference …
Experimental Verification Of Near-Wall Hindered Diffusion Theory For The Brownian Motion Of Nanoparticles Using Evanescent Wave Microscopy, Kenneth D. Kihm, Arindam Banerjee
Experimental Verification Of Near-Wall Hindered Diffusion Theory For The Brownian Motion Of Nanoparticles Using Evanescent Wave Microscopy, Kenneth D. Kihm, Arindam Banerjee
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A total internal reflection fluorescence microscopy technique coupled with three-dimensional tracking of nanoparticles is used to experimentally verify the theory on near-wall hindered Brownian motion [Goldman et al., Chem. Eng. Sci. 22, 637 (1967); Brenner, Chem. Eng. Sci. 16, 242 (1967)] very close to the solid surface (within ~1 µm). The measured mean square displacements (MSDs) in the lateral x-y directions show good agreement with the theory for all tested nanoparticles of radii 50, 100, 250, and 500 nm. However, the measured MSDs in the z direction deviate substantially from the theory particularly for the case of smaller particles of …
Modular Control Laboratory System With Integrated Simulation, Animation, Emulation, And Experimental Components, J. Liu, Robert G. Landers
Modular Control Laboratory System With Integrated Simulation, Animation, Emulation, And Experimental Components, J. Liu, Robert G. Landers
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A typical sequence for the design of a controller, given the desired objectives, is the following: system modeling, design and mathematical analysis, simulation studies, emulation, and experimental implementation. Most control courses thoroughly cover design and mathematical analysis and utilize a simulation or experimental project at the end of the course. However, animation and emulation are seldom utilized and projects rarely cover the entire controller design sequence. This paper presents a control laboratory system developed at the University of Missouri at Rolla that integrates simulation, animation, emulation, and experimental components. The laboratory system may be applied to a wide variety of …
Optimal Control Of A Class Of One-Dimensional Nonlinear Distributed Parameter Systems With Discrete Actuators, Radhakant Padhi, S. N. Balakrishnan
Optimal Control Of A Class Of One-Dimensional Nonlinear Distributed Parameter Systems With Discrete Actuators, Radhakant Padhi, S. N. Balakrishnan
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Combining the principles of dynamic inversion and optimization theory, a new approach is presented for stable control of a class of one-dimensional nonlinear distributed parameter systems with a finite number of actuators in the spatial domain. Unlike the existing ''approximate-then-design'' and ''design-then-approximate'' techniques, this approach does not use any approximation either of the system dynamics or of the resulting controller. The formulation has more practical significance because one can implement a set of discrete controllers with relative ease. To demonstrate the potential of the proposed technique, a real-life temperature control problem for a heat transfer application is solved through simulations. …
Stochastic Optimal Control With Neural Networks And Application To A Retailer Inventory Problem, Zhongwu Huang, Xiaohua Wang, S. N. Balakrishnan
Stochastic Optimal Control With Neural Networks And Application To A Retailer Inventory Problem, Zhongwu Huang, Xiaohua Wang, S. N. Balakrishnan
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Overwhelming computational requirements of classical dynamic programming algorithms render them inapplicable to most practical stochastic problems. To overcome this problem a neural network based Dynamic Programming (DP) approach is described in this study. The cost function which is critical in a dynamic programming formulation is approximated by a neural network according to some designed weight-update rule based on Temporal Difference(TD)learning. A Lyapunov based theory is developed to guarantee an upper error bound between the output of the cost neural network and the true cost. We illustrate this approach through a retailer inventory problem.
A Methodology For Model Selection In Engineering Design, Rajesh Radhakrishnan, Daniel A. Mcadams
A Methodology For Model Selection In Engineering Design, Rajesh Radhakrishnan, Daniel A. Mcadams
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Engineering design consists of a series of stages during which a number of decisions need to be made by the designer. Since the information available to the designer is limited during initial design stages, to make these decisions and be able to proceed further in the design process, the designer needs to depict the nature, visualize the form, and predict the behavior of the product through the use of aids called models. These models guide these decisions; therefore, the designer needs to ensure the downstream validity of these decisions by constructing models with sufficient accuracy and resolution. Because higher quality …
A Model Of Function-Based Representations, Michael Van Wie, Cari R. Bryant, Matt R. Bohm, Robert B. Stone, Daniel A. Mcadams
A Model Of Function-Based Representations, Michael Van Wie, Cari R. Bryant, Matt R. Bohm, Robert B. Stone, Daniel A. Mcadams
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The need to model and to reason about design alternatives throughout the design process demands robust representation schemes of function, behavior, and structure. Function describes the physical effect imposed on an energy or material flow by a design entity without regard for the working principles or physical solutions used to accomplish this effect. Behaviors are the physical events associated with a physical artifact (or hypothesized concept) over time (or simulated time) as perceived by an observer. Structure, the most tangible concept, partitions an artifact into meaningful constituents such as features, Wirk elements, and interfaces in addition to the widely used …
Optimal And Hierarchical Formation Control For Uav, Xiaohua Wang, S. N. Balakrishnan
Optimal And Hierarchical Formation Control For Uav, Xiaohua Wang, S. N. Balakrishnan
Mechanical and Aerospace Engineering Faculty Research & Creative Works
In this paper, optimal and hierarchical control concepts are investigated for cooperative formation flying of aircrafts. The airplanes are modeled as point mass and represented by double integrators. And all the planes are considered to be in a plane. For demonstration of the concepts, a task of forming a square from arbitrary initial conditions is presented to four airplanes. The final position that each airplane has to reach is unknown to them. The goal for the team is abstracted in the top layer. The system is modeled as a two layer hierarchical system in which the global information comes from …