Engineering Commons^™

Constrained Nonlinear Heuristic-Based Mpc For Control Of Robotic Systems With Uncertainty, Tyler James Quackenbush

Theses and Dissertations

This thesis focuses on the development and extension of nonlinear evolutionary model predictive control (NEMPC), a control algorithm previously developed by Phil Hyatt of the BYU RaD Lab. While this controller and its variants are applicable to any high degree-of-freedom (DoF) robotic system, particular emphasis is given in this thesis to control of a soft robot continuum joint. First, speed improvements are presented for NEMPC. Second, a Python package is presented as a companion to NEMPC, as a method of establishing a common interface for dynamic simulators and approximating each system by a deep neural network (DNN). Third, a method …

Robust Real-Time Model Predictive Control For High Degree Of Freedom Soft Robots, Phillip Edmond Hyatt

Theses and Dissertations

This dissertation is focused on the modeling and robust model-based control of high degree-of-freedom (DoF) systems. While most of the contributions are applicable to any difficult-to-model system, this dissertation focuses specifically on applications to large-scale soft robots because their many joints and pressures constitute a high-DoF system and their inherit softness makes them difficult to model accurately. First a joint-angle estimation and kinematic calibration method for soft robots is developed which is shown to decrease the pose prediction error at the end of a 1.5 m robot arm by about 85\%. A novel dynamic modelling approach which can be evaluated …

Optimization-Based Spatial Positioning And Energy Management For Unmanned Aerial Vehicles, Ronald Abraham Martin

Theses and Dissertations

This research applies techniques from the field of optimization to spatial positioning and energy management in Unmanned Aerial Vehicles (UAVs). Two specific areas are treated: optimization of UAV view plans for 3D modeling of infrastructure, and trajectory optimization of solar powered high-altitude long-endurance (HALE) UAVs. Structure-from-Motion (SfM) is a computer vision technique for creating 3D models from 2D images. View planning is the process of planning image sets that will effectively model a given scene. First, a genetic algorithm based view planning approach is demonstrated. A novel terrain simulation environment is developed, and the algorithm is tested at multiple sites …

Visual Servoing For Multirotor Precision Landing In Varying Light Conditions, Jesse Wynn, Tim Mclain

Faculty Publications

The problem of performing a precision landing of an autonomous multirotor UAV in various lighting conditions is studied. A vision-based approach is proposed and consists of varying degree-of-freedom image-based visual servoing (VDOF-IBVS), and a specialized landing marker. The proposed approach is validated through extensive flight testing outdoors in both lighted and dark conditions, and is done using a standard off-the-shelf autopilot system.

Investigation And Implementation Of A Robust Temperature Control Algorithm For Friction Stir Welding, Kenneth A. Ross

Theses and Dissertations

In friction stir welding, the temperature of the process zone affects the properties of the resulting weld and has a dramatic effect on tool life in PCBN (polycrystalline cubic boron nitride) tools. Therefore an active control system that changes process parameters to control weld temperature is desirable. Mayfield and Sorensen proposed a two-stage control model that contains an inner loop that controls the spindle speed to keep power constant and an outer loop for setting the desired power based on weld temperature. This work contains the analysis and implementation of a temperature control method based on their work. This research …

Development Of A Particle Flow Test For Rotational Molding, Russell B. Whatcott

Theses and Dissertations

One of the current testing method (the Dry Flow test) to qualify resin for use in production in the rotomolding process has been shown to have many flaws in both equipment and procedure. Research was done here to investigate a possible alternative that could eliminate some of these testing deficiencies. By reducing equipment and operator errors, the testing of materials becomes more valuable of an exercise. The Angular Flow test developed in this research can increase repeatability. By coming to understand the rotational molding process better, an evaluation that can give more valid information was devised.

Real-Time Implementation Of Vision Algorithm For Control, Stabilization, And Target Tracking For A Hovering Micro-Uav, Beau J. Tippetts

Theses and Dissertations

A lightweight, powerful, yet efficient quad-rotor platform was designed and constructed to obtain experimental results of completely autonomous control of a hovering micro-UAV using a complete on-board vision system. The on-board vision and control system is composed of a Helios FPGA board, an Autonomous Vehicle Toolkit daughterboard, and a Kestrel Autopilot. The resulting platform is referred to as the Helio-copter. An efficient algorithm to detect, correlate, and track features in a scene and estimate attitude information was implemented with a combination of hardware and software on the FPGA, and real-time performance was obtained. The algorithms implemented include a Harris feature …

Active Minimization Of Acoustic Energy Density To Attenuate Radiated Noise From A Diesel Generator, Andrew J. Boone

Theses and Dissertations

The focus of this thesis was to use active noise control (ANC) to globally minimize the tonal and broadband noise radiating from a diesel generator enclosure. The major goal of this research was to show that minimizing the noise within the enclosure can lead to an overall sound pressure level (SPL) reduction of radiated noise. The target levels for overall SPL reduction were at least 2 dBA. The control algorithms used in this research were based on a filtered-x LMS adaptive algorithm, which minimizes energy density (ED). Both feedforward and feedback control approaches were investigated. The noise spectrum produced by …

Adaptive Control Of Micro Air Vehicles, Joshua Stephen Matthews

Theses and Dissertations

Although PID controllers work well on Miniature Air Vehicles (MAVs), they require tuning for each MAV. Also, they quickly lose performance in the presence of actuator failures or changes in the MAV dynamics. Adaptive control algorithms that self tune to each MAV and compensate for changes in the MAV during flight are explored. However, because the autopilots on MAVs are small, many of the adaptive control algorithms like those that employ least squares estimation may take too much code space, memory, and/or computing power. In this thesis we develop several Lyapunov-based model reference adaptive control (MRAC) schemes that are both …

Preliminary Modeling, Control, And Trajectory Design For Miniature Autonomous Tailsitters, Nathan B. Knoebel, Stephen R. Osborne, Deryl Snyder, Timothy W. Mclain, Randal W. Beard, Andrew Mark Eldredge

Faculty Publications

A tailsitter UAV has unique advantages over typical fixed wing aircraft or hovercraft. This paper highlights topics of interest in our preliminary research in developing a tailsitter UAV. An aerodynamic model and quaternion-based attitude and position control scheme is presented for controlling a tailsitter through hover maneuvers, with simulation results. Desired trajectories are also developed through feedback linearization of the dynamic equations, intended for quaternion-based attitude control. Finally, a hardware platform is proposed.

Settling-Time Improvements In Positioning Machines Subject To Nonlinear Friction Using Adaptive Impulse Control, Tim Hakala

Theses and Dissertations

A new method of adaptive impulse control is developed to precisely and quickly control the position of machine components subject to friction. Friction dominates the forces affecting fine positioning dynamics. Friction can depend on payload, velocity, step size, path, initial position, temperature, and other variables. Control problems such as steady-state error and limit cycles often arise when applying conventional control techniques to the position control problem. Studies in the last few decades have shown that impulsive control can produce repeatable displacements as small as ten nanometers without limit cycles or steady-state error in machines subject to dry sliding friction. These …

An Open Architecture For Versatile Machine And Actuator Control, Michael Scott Baxter

Theses and Dissertations

Automatic control technology increases usability, reliability and productivity in manufacturing, transportation, and climate control. There are many additional areas of modern life that could benefit through automatic control; however, current automation components are too expensive or aren't sufficiently flexible. For example, the cost of current commercial motion control components precludes their use in an average home. This thesis describes an automatic control methodology that is low cost and is flexible enough for a wide variety of control applications. Typical applications could include:

- Home lighting, security and appliances

- Commercial building heating, ventilation and air conditioning

- Industrial machine tool …

Boundary Control For Automated Sweeping Of Finite Element Meshes, Robert A. Kerr

Theses and Dissertations

Finite element analysis depends greatly upon a high-quality mesh to be able to provide reasonably accurate answers to engineering problems. Models that need to be analyzed using finite element analysis are becoming increasingly more complex, and correspondingly harder to mesh with good quality. Skew is one quality metric which can cause problems with finite element analyses. This thesis explains how skew is calculated, discusses two common sources of skew: multiply-linked surfaces with interval constraints, and biased edge meshes. Two methods of lessening skew in surface meshes are then presented: the skew control algorithm, and the curve morphing algorithm. These algorithms …

Interval Matching And Control For Hexahedral Mesh Generation Of Swept Volumes, Jason F. Shepherd

Theses and Dissertations

Surface meshing algorithms require certain relationships among the number of intervals on the curves that bound the surface. Assigning the number of intervals to all of the curves in the model such that all relationships are satisfied is called interval assignment. Volume meshing algorithms also require certain relationships among the numbers of intervals on each of the curves on the volume. These relationships are not always captured by surface meshing requirements. This thesis presents a news technique for automatically identifying volume constraints. In this technique, volume constraints are grouped with surface constraints and are solved simultaneously. A sweepable volume has …