This thesis presents the design, construction, and control of a two-wheeled inverted pendulum (TWIP) robotic walker prototype for assisting mobility-impaired users with balance and fall prevention. A conceptual model of the robotic walker is developed and used to illustrate the purpose of this study. A linearized mathematical model of the two-wheeled system is derived using Newtonian mechanics. A control strategy consisting of a decoupled LQR controller and three state variable controllers is developed to stabilize the platform and regulate its behavior with robust disturbance rejection performance. Simulation results reveal that the LQR controller is capable of stabilizing the platform and rejecting external disturbances while the state variable controllers simultaneously regulate the system’s position with smooth and minimum jerk control. A prototype for the two-wheeled system is fabricated and assembled followed by the implementation and tuning of the control algorithms responsible for stabilizing the prototype and regulating its position with optimal performance. Several experiments are conducted, confirming the ability of the decoupled LQR controller to robustly balance the platform while the state variable controllers regulate the platform’s position with smooth and minimum jerk control.

The research attempts to provide a graphical theory-based approach to solve the facility layout problem. Which has generally been approached using Quadratic Assignment Problem (QAP) in the past, an algebraic method. It is a very complex problem and is part of the NP-Hard optimization class, because of the nonlinear quadratic objective function and (0,1) binary variables. The research is divided into three phases which together provide an optimal facility layout, block plan solution consisting of MHS (material handling solution) projected onto the block plan. In phase one, we solve for the position of departments in a facility based on flow and utility factor (weight for location). The position of all the departments is identified on the vertices of MPG (maximal planar graph), which maximizes the possibility of flow. We use named MPG produced in literature, throughout the research. The grouping of the department is achieved through GMAFLAD, a QSP (quadratic set packing) based optimizer. In Phase 2, the dual for the MPG’s is solved consisting of department location as per phase 1, to generate Voronoi graphs. These graphs are then, expanded by an ingenious parameter optimization formulation to achieve area fitting for individual cases. Optimization modeling software, Lingo17.0 is used for solving the parameter optimization for generating coordinates of the block plan. The plotting of coordinates for the block plan graphics is done via Autodesk inventor 2019. In phase 3, the solution for MHS is achieved using an RSMT (Rectilinear Steiner minimal tree) graph approach. The Voronoi seed coordinates produced through phase 2 results are computed by GeoSteiner package to generated the RSMT graph for projection onto the block plan (Also, done by Inventor 2019). The graphical method employed in this research, itself has complex and NP-hard problem segments in it, which have been relaxed to polynomial time complexity by fragmenting into groups and solving them in sections. Solving for MPG & RSMT are a class of NP-Hard problem, which have been restricted to N=32 here. Finally, to validate the research and its methodology a real-life case study of a shipyard building for the data set of PDVSA, Venezuela is performed and verified.

Carbon fiber reinforced composites are utilized in many design applications where high strength, low weight, and/or high stiffness are required. While composite materials can provide high strength and stiffness-to-weight ratios, they are also more complicated to analyze due to their inhomogeneous nature. One important failure mode of composite structures is delamination. This failure mode is common when composite laminates are subject to impact loading. Various finite element methods for analyzing delamination exist. In this research, a modeling strategy based on contact tiebreak definitions in LS-DYNA®was used. A finite element model of a low-velocity impact event was created to predict delamination in a composite laminate. The resulting delamination relative size and shape was found to partially agree with analytical and experimental results for similar impact events, while the force-time plot agreed well with experimental results. A small difference in contact time in the simulation compared to experimental testing is likely due to the omission of composite failure modes other than delamination. Experimental impact testing and subsequent vibrothermography analysis showed delamination damage in locations shown in previous research. This confirmed the validity of vibrothermography as a nondestructive evaluation technique for analyzing post-impact delamination.

The manufacture, laminate design, and modeling of a part with complex geometry are explored. The ultimate goal of the research is to produce a model that accurately predicts part stiffness. This is validated with experimental results of composite parts, which refine material properties for use in a final prototype part model. The secondary goal of this project is to explore manufacturing methods for improved manufacturability of the complex part. The manufacturing portion of the thesis and feedback into material model has incorporated a senior project team to perform research on manufacturing and create composite part to be used for experimental testing. The senior project was designed, led, and managed by the author with support from the committee chair. Finite element modeling was refined using data from coupon 3-point bend testing to improve estimates on material properties. These properties were fed into a prototype part model which predicted deflection of composite parts with different layups and materials. The results of the model were compared to experimental results from prototype part testing and 3rd party analysis. The results showed that an accurate mid-plane shell element model could be used to accurately predict deflection for 2 of 3 experimental parts. There are recommendations in the thesis to further validate the models and experimental testing.

Lawrence Livermore National Lab (LLNL) is home to the National Ignition Facility (NIF), the world’s largest and most energetic laser. Each of the 192 beamlines contains dozens of large optics, which require offline damage inspection using large, raster-scanning microscopes. The primary microscope used to measure and characterize the optical damage sites has a precision level of 1 µm. Mounted in a class 100 clean room with a raised tile floor, the microscope is supported by a steel stand that structurally connects the microscope to the concrete ground. Due to ambient vibrations experienced in the system, the microscope is only able to reliably reach a 10-µm level of precision. As NIF’s technology advances, there is a need to both increase optic measurement throughput and to measure damage sites at a higher level of precision. As a result, there is to be another microscope mounted into another clean room lab at LLNL. To assure the microscope can meet its specified level of precision, the stand on which it is mounted was designed to meet the rigorous Environmental Vibrational Criteria standards, or VC curves. Through the collection of random vibrational data using accelerometers and Power Spectral Density (PSD) analysis, the stand was designed to meet the VC-C curve requirement of velocities below 12.5 µm/sec. Furthermore, the stand design was optimized to avoid resonance at common vibrational signatures throughout the frequency spectrum, placing its first natural frequency at a sufficiently high level to minimize amplification.

The semestral project will focus on using Computer Aided Engineering for analysis of the ESEM differential chamber. The instruments used for the analysis, evaluation and scrutiny of the given issue will be the CAD and CAE systems (Computer Aided Design and Computer Aided Engineering).

Modern lower limb prostheses are devices that replace missing limbs, making it possible for lower limb amputees to walk again. Most commercially available prosthetic limbs lack intelligence and passive adaptive capabilities, and none available can adapt on a step by step basis. Often, amputees experience a loss of terrain adaptability as well as stability, leaving the amputee with a severely altered gait. This work is focused on the development of a semi-active damping system for use in intelligent terrain adaptive ankle prostheses. The system designed consists of an optimized hydraulic cylinder with an electronic servo valve which throttles the hydraulic fluid flowing between the cylinder’s chambers, acting on the prosthesis joint with a moment arm in series with a carbon spring foot. This provides the capability to absorb energy during the amputees gait cycle in a controlled manner, effectively allowing the passive dynamic response to be greatly altered continuously by leveraging a small energy source. A virtual simulation of an amputee gait cycle with the adaptive semi-active ankle design revealed the potential to replicate adaptive abilities of the human ankle. The results showed very similarly that irregularities in amputee biomechanics can be greatly compensated for using semi-active damping.

Asymmetric bending is explored as a means of inducing bend-twist coupling in an isotropic, fixed-wing airfoil. An analytical model describing the bend-twist coupling behavior of a constant-section airfoil undergoing steady wind loading is derived from Euler-Bernoulli beam theory, and evaluated over a range of structural and material stiffness. Finite element analysis is carried out in the ANSYS Parametric Design Language environment for an asymmetric, two-dimensional beam. Three-dimensional finite element analysis is carried out for two candidate blade models created in Pro/Engineer based on the NACA 64618 airfoil. Deformation results for the two- and three-dimensional finite element models are compared with analytical solutions. Results of this investigation highlight the dependency between the cross-sectional properties of a spar support and its tendency to exhibit twist-coupling under transverse loading.

The current generation wind turbines are upscaled into multi megawatt range in terms of output power. However, the energy benefit from the turbine is offset by the increased mass and cost. Twenty MW wind turbines are now feasible with rotor diameters up to 200 m, according to a new report from the EU-funded UpWind project in 2011. The question is, how much bigger can wind turbines get realistically? One concept worth considering, and the one that is the subject of this thesis, is to have more than one rotor on a single support structure. Such turbines could have a greater power to weight ratio. Multi-rotor systems also offer the advantage of standardization, transportation and ease of installation and maintenance. In this thesis the NREL 5 MW single rotor baseline wind turbine is compared with a 5 MW multi-rotor wind turbine. The multiple rotors are downscaled using scaling curves keeping the 5 MW baseline machine as reference.

Walkers provided stability to the elderly but cannot assist a person from sitting to standing. The objective of this project is to present the design and analysis of a lift assist walker. This report discusses the design and analysis of a collapsible lift assist walker capable of lifting a patient up to 250 lbs. from seated to standing in under 10 seconds. The designed walker utilized a two stage scissor mechanism with a gas spring assisted embedded linear actuator.