Aerospace Engineering Commons^™

Formation Control With Collision Avoidance For Fixed-Wing Unmanned Air Vehicles With Speed Constraints, Christopher Heintz

Theses and Dissertations--Mechanical Engineering

Advances in the miniaturization of powerful electronic components and motors, the democratization of global navigation satellite systems (GNSS), and improvements in the performance, safety, and cost in lithium batteries has led to the proliferation of small and relatively inexpensive unmanned aerial vehicles (UAVs). Many of these UAVs are of the multi-rotor design, however, fixed-wing designs are often more efficient than rotary-wing aircraft, leading to a reduction in the power required for a UAV of a given mass to stay airborne. Autonomous cooperation between multiple UAVs would enable them to complete objectives that would be difficult or impossible for a single …

Electromagnetic Formation Control Using Frequency Multiplexing, Zahra Abbasi

Theses and Dissertations--Mechanical Engineering

This dissertation addresses control of relative positions and orientations of formation flying satellites using magnetic interactions. Electromagnetic formation flight (EMFF) is implemented, in which each satellite is equipped with a set of electromagnetic coils to generate an electromagnetic field. Traditional EMFF technique applies DC magnetic fields which lead to a nonlinear and highly coupled formation dynamics that allow for only position or orientation control of the satellites. We present a new frequency multiplexing method, which is a technique that uses multi-frequency sinusoidal controls, to approximately decouple the formation dynamics and to provide enough controls for both position and orientation control. …

Attitude Control And Consensus On So(3) Using Sinusoids: Theory And Application To Small Satellites, Roshan Anandrao Chavan

Theses and Dissertations--Mechanical Engineering

We present and analyze kinematic-level and dynamic-level feedback control algorithms for single agent attitude control and multi-agent attitude consensus on SO(3). The kinematic-level algorithms yield attitude feedback controls that are piecewise-continuous sinusoidal angular velocities. The dynamic-level algorithms yield attitude feedback controls that are relative angles of rotational-mass actuators, which are continuous but only piecewise continuously differentiable sinusoids. Furthermore, the dynamic-level algorithms are designed to accommodate actuator stroke constraint. We present application of the dynamic-level control algorithms to attitude control and consensus of small-satellites.

Single-Degree-Of-Freedom Experiments Demonstrating Electromagnetic Formation Flying For Small Satellite Swarms Using Piecewise-Sinusoidal Controls, Ajin Sunny

Theses and Dissertations--Mechanical Engineering

This thesis presents a decentralized electromagnetic formation flying (EMFF) control method using frequency-multiplexed sinusoidal control signals. We demonstrate the EMFF control approach in open-loop and closed-loop control experiments using a single-degree-of-freedom testbed with an electromagnetic actuation system (EAS). The EAS sense the relative position and velocity between satellites and implement a frequency-multiplexed sinusoidal control signal. We use a laser-rangefinder device to capture the relative position and an ARM-based microcontroller to implement the closed-loop control algorithm. We custom-design and build the EAS that implements the formation control in one dimension. The experimental results in this thesis demonstrate the feasibility of the …

Considerations For Atmospheric Measurements With Small Unmanned Aircraft Systems, Jamey D. Jacob, Phillip B. Chilson, Adam L. Houston, Suzanne Weaver Smith

Mechanical Engineering Faculty Publications

This paper discusses results of the CLOUD-MAP (Collaboration Leading Operational UAS Development for Meteorology and Atmospheric Physics) project dedicated to developing, fielding, and evaluating integrated small unmanned aircraft systems (sUAS) for enhanced atmospheric physics measurements. The project team includes atmospheric scientists, meteorologists, engineers, computer scientists, geographers, and chemists necessary to evaluate the needs and develop the advanced sensing and imaging, robust autonomous navigation, enhanced data communication, and data management capabilities required to use sUAS in atmospheric physics. Annual integrated evaluation of the systems in coordinated field tests are being used to validate sensor performance while integrated into various sUAS platforms. …

Discrete-Time Adaptive Control Algorithms For Rejection Of Sinusoidal Disturbances, Mohammadreza Kamaldar

Theses and Dissertations--Mechanical Engineering

We present new adaptive control algorithms that address the problem of rejecting sinusoids with known frequencies that act on an unknown asymptotically stable linear time-invariant system. To achieve asymptotic disturbance rejection, adaptive control algorithms of this dissertation rely on limited or no system model information. These algorithms are developed in discrete time, meaning that the control computations use sampled-data measurements. We demonstrate the effectiveness of algorithms via analysis, numerical simulations, and experimental testings. We also present extensions to these algorithms that address systems with decentralized control architecture and systems subject to disturbances with unknown frequencies.

Autonomous Quadrotor Collision Avoidance And Destination Seeking In A Gps-Denied Environment, Thomas C. Kirven

Theses and Dissertations--Mechanical Engineering

This thesis presents a real-time autonomous guidance and control method for a quadrotor in a GPS-denied environment. The quadrotor autonomously seeks a destination while it avoids obstacles whose shape and position are initially unknown. We implement the obstacle avoidance and destination seeking methods using off-the-shelf sensors, including a vision-sensing camera. The vision-sensing camera detects the positions of points on the surface of obstacles. We use this obstacle position data and a potential-field method to generate velocity commands. We present a backstepping controller that uses the velocity commands to generate the quadrotor's control inputs. In indoor experiments, we demonstrate that the …

Small Satellite Noncommutative Rotation Sequence Attitude Control Using Piezoelectric Actuators, Joshua L. Evans

Theses and Dissertations--Electrical and Computer Engineering

Attitude control remains one of the top engineering challenges faced by small satellite mission planning and design. Conventional methods for attitude control include propulsion, reaction wheels, magnetic torque coils, and passive stabilization mechanisms, such as permanent magnets that align with planetary magnetic fields. Drawbacks of these conventional attitude control methods for small satellites include size, power consumption, dependence on external magnetic fields, and lack of full control authority. This research investigates an alternative, novel approach to attitude-control method for small satellites, utilizing the noncommutative property of rigid body rotation sequences. Piezoelectric bimorph actuators are used to induce sinusoidal small-amplitude satellite …

Filtered-Dynamic-Inversion Control For Fixed-Wing Unmanned Aerial Systems, Jon Mullen

Theses and Dissertations--Mechanical Engineering

Instrumented umanned aerial vehicles represent a new way of measuring turbulence in the atmospheric boundary layer. However, autonomous measurements require control methods with disturbance-rejection and altitude command-following capabilities. Filtered dynamic inversion is a control method with desirable disturbance-rejection and command-following properties, and this controller requires limited model information. We implement filtered dynamic inversion as the pitch controller in an altitude-hold autopilot. We design and numerically simulate the continuous-time and discrete-time filtered-dynamic-inversion controllers with anti-windup on a nonlinear aircraft model. Finally, we present results from a flight experiment comparing the filtered-dynamic-inversion controller to a classical proportional-integral controller. The experimental results show …

Visual Attitude Propagation For Small Satellites, Samir Ahmed Rawashdeh

Theses and Dissertations--Electrical and Computer Engineering

As electronics become smaller and more capable, it has become possible to conduct meaningful and sophisticated satellite missions in a small form factor. However, the capability of small satellites and the range of possible applications are limited by the capabilities of several technologies, including attitude determination and control systems. This dissertation evaluates the use of image-based visual attitude propagation as a compliment or alternative to other attitude determination technologies that are suitable for miniature satellites. The concept lies in using miniature cameras to track image features across frames and extracting the underlying rotation.

The problem of visual attitude propagation as …

An Attitude Determination System With Mems Gyroscope Drift Compensation For Small Satellites, Maxwell Bezold

Theses and Dissertations--Electrical and Computer Engineering

This thesis presents the design of an attitude determination system for small satellites that automatically corrects for attitude drift. Existing attitude determination systems suffer from attitude drift due to the integration of noisy rate gyro sensors used to measure the change in attitude. This attitude drift leads to a gradual loss in attitude knowledge, as error between the estimated attitude and the actual attitude increases.

In this thesis a Kalman filter is used to complete sensor fusion which combines sensor observations with a projected attitude based on the dynamics of the satellite. The system proposed in this thesis also utilizes …