Mechanical Engineering Commons^™

Evaluation Of Different Optimal Control Problem Formulations For Solving The Muscle Redundancy Problem, Friedl De Groote, Allison Kinney, Anil Rao, Benjamin J. Fregly

Mechanical and Aerospace Engineering Faculty Publications

This study evaluates several possible optimal control problem formulations for solving the muscle redundancy problem with the goal of identifying the most efficient and robust formulation. One novel formulation involves the introduction of additional controls that equal the time derivative of the states, resulting in very simple dynamic equations. The nonlinear equations describing muscle dynamics are then imposed as algebraic constraints in their implicit form, simplifying their evaluation. By comparing different problem formulations for computing muscle controls that can reproduce inverse dynamic joint torques during gait, we demonstrate the efficiency and robustness of the proposed novel formulation.

Wing Tip Vortices From An Exergy-Based Perspective, Muhammad Omar Memon, Kevin Wabick, Aaron Altman, Rainer M. Buffo

Mechanical and Aerospace Engineering Faculty Publications

The lens of exergy is used to investigate a wingtip vortex in the near wake over a range of angles of attack. Exergy is the measure of thermodynamically “available” energy as determined through the more discriminating second law of thermodynamics. Experiments were conducted in a water tunnel at Institute of Aerospace Systems at Aachen.

The data were taken three chord lengths downstream in the Trefftz plane of an aspect ratio 5 Clark-Y wing with a square-edged wing tip using particle image velocimetry. Intuitively, the minimum available energy state is expected to correspond to the maximum lift-to-drag ratio angle of attack. …

Development Of A Muscle Model Parameter Calibration Method Via Passive Muscle Force Minimization, Allison Kinney, Benjamin J. Fregly

Mechanical and Aerospace Engineering Faculty Publications

Computational predictions of subject-specific muscle and knee joint contact forces during walking may improve individual rehabilitation treatment design. Such predictions depend directly on specified model parameter values. However, model parameters are difficult to measure non-invasively. Methods for muscle model parameter calibration have been developed previously. However, it is currently unknown how the musculoskeletal system chooses muscle model parameter values. Previous studies have hypothesized that muscles avoid injury during walking by generating little passive force and operating in the ascending region of the force-length curve. This hypothesis suggests that muscle model parameter values may be selected by the body to minimize …

Synergy-Based Two-Level Optimization For Predicting Knee Contact Forces During Walking, Gil Serrancolí, Allison Kinney, Josep M. Font-Llagunes, Benjamin J. Fregly

Mechanical and Aerospace Engineering Faculty Publications

Musculoskeletal models and optimization methods are combined to calculate muscle forces. Some model parameters cannot be experimentally measured due to the invasiveness, such as the muscle moment arms or the muscle and tendon lengths. Moreover, other parameters used in the optimization, such as the muscle synergy components, can be also unknown. The estimation of all these parameters needs to be validated to obtain physiologically consistent results. In this study, a two-step optimization problem was formulated to predict both muscle and knee contact forces of a subject wearing an instrumented knee prosthesis. In the outer level, muscle parameters were calibrated, whereas …

Hydrogen And Syngas Production From Gasification Of Lignocellulosic Biomass In Supercritical Water Media, Jun-Ki Choi, Abtin Ataei, Ahmad Tavasoli, Farid Safari

Mechanical and Aerospace Engineering Faculty Publications

Novel biomass-processing technologies have been recently used for conversion of organic wastes into valuable biofuels like bio-hydrogen. Agricultural wastes are available and renewable energy resources to supply energy demand of the future. The purpose of this study is to investigate the production of hydrogen-rich syngas from wheat straw, walnut shell, and almond shell.

The Influence Of Neuromusculoskeletal Model Calibration Method On Predicted Knee Contact Forces During Walking, Gil Serrancolí, Allison Kinney, Benjamin J. Fregly, Josep M. Font-Llagunes

Mechanical and Aerospace Engineering Faculty Publications

This study explored the influence of three model calibration methods on predicted knee contact and leg muscle forces during walking. Static optimization was used to calculate muscle activations for all three methods. Approach A used muscle-tendon model parameter values (i.e., optimal muscle fiber lengths and tendon slack lengths) taken directly from literature. Approach B used a simple algorithm to calibrate muscle-tendon model parameter values such that each muscle operated within the ascending region of its normalized force-length curve. Approach C used a novel two-level optimization procedure to calibrate muscle-tendon, moment arm, and neural control model parameter values while simultaneously predicting …

Intrusion Detection In Aerial Imagery For Protecting Pipeline Infrastructure, Paheding Sidike, Almabrok Essa, Vijayan K. Asari

Electrical and Computer Engineering Faculty Publications

We present an automated mechanism that can detect and issue warnings of machinery threat such as the presence of construction vehicles on pipeline right-of-way. The proposed scheme models the human visual perception concepts to extract fine details of objects by utilizing the corners and gradient histogram information in pyramid levels. Two real-world aerial image datasets are used for testing and evaluation.

School-Books On Tape: The Tensile And Adhesive Strength Of Duct Tape In A College Backpack, Robin Elizabeth Ker

Honors Theses

Two categories were used to assess the strength of duct tape constructions: adhesive strength and tensile strength. Previously made duct tape backpacks frequently suffered from adhesive failure around shoulder straps. When a backpack is lifted, it experiences a force which is greater than the resting weight. The hypothesis states that there is an area of application between two pieces of duct tape such that they will behave as a uniform piece and experience tensile failure, that two sufficiently overlapped pieces can hold within 5% of the load carried by a single piece, and that there is a relationship between the …

Multi-Segment Foot Joint Kinematics With Varying Midfoot Orthotic Postings, Hilary F. Feskanin

Honors Theses

Foot orthoses are often prescribed to prevent and treat lower limb disorders. While the success of these devices is well documented, the mechanisms behind them are unclear. Due to methodological limitations, many studies have focused on the rearfoot. This is the first study to assess the effects of midfoot-targeted orthotic strategies on midfoot and rearfoot kinematics. Gait mechanics were recorded for 19 healthy females walking in four orthotic conditions: valgus midfoot post, varus midfoot post, heel lift and standard/control. The midtarsal and ankle joint 3D kinematics for the three experimental conditions were compared to the control condition. Variables of interest …

A Mechanical Regenerative Brake And Launch Assist Using An Open Differential And Elastic Energy Storage, David H. Myszka, Andrew P. Murray, Kevin Giaier, Vijay Krishna Jayaprakash, Christoph Gillum

Mechanical and Aerospace Engineering Faculty Publications

Regenerative brake and launch assist (RBLA) systems are used to capture kinetic energy while a vehicle decelerates and subsequently use that stored energy to assist propulsion. Commercially available hybrid vehicles use generators, batteries and motors to electrically implement RBLA systems. Substantial increases in vehicle efficiency have been widely cited.

This paper presents the development of a mechanical RBLA that stores energy in an elastic medium. An open differential is coupled with a variable transmission to store and release energy to an axle that principally rotates in a single direction. The concept applies regenerative braking technology to conventional automobiles equipped with …

Simulating Energy Efficient Control Of Multiple-Compressor Compressed Air Systems, Sean Murphy, J. Kelly Kissock

Mechanical and Aerospace Engineering Faculty Publications

In many industrial facilities it is common for more than one air compressor to be operating simultaneously to meet the compressed air demand. The individual compressor set-points and how these compressors interact and respond to the facility demand have a significant impact on the compressed air system total power consumption and efficiency. In the past, compressors were staged by cascading the pressure band of each compressor in the system. Modern automatic sequencers now allow more intelligent and efficient staging of air compressors.

AirSim, a compressed air simulation tool, is now able to simulate multiple-compressor systems with pressure band and automatic …

A Multi-Directional Treadmill Training Program For Improving Gait, Balance, And Mobility In Individuals With Parkinson’S Disease: A Case Series, Kimberly Smith, Kurt Jackson, Kimberly Edginton Bigelow, Lloyd L. Laubach

Mechanical and Aerospace Engineering Faculty Publications

Treadmill training is a commonly used intervention for improving gait in people with Parkinson’s disease (PD). However, little is known about how treadmill training may also influence balance and other aspects of mobility.

The purpose of this case series was to explore the feasibility and possible benefits of multi-directional treadmill training for individuals with PD. Four participants (62.3 ± 6.5 yrs, Hoehn & Yahr 2-4) performed 8 weeks of treadmill training 3 times per week. Weeks 1-4 included forward walking only, while weeks 5-8 included forward and multi-directional walking. Participants were tested every 4 weeks on 4 separate occasions. Outcome …