Engineering Commons^™

Utilizing An Improved Rotorcraft Dynamic Model In State Estimation, Timothy Mclain, Randal W. Beard, Robert C. Leishman, John Macdonald, Jeffrey L. Ferrin, Stephen C. Quebe

Faculty Publications

Multirotor aircraft have become a popular platform for indoor flight. To navigate these vehicles indoors through an unknown environment requires the use of a SLAM algorithm, which can be processing intensive. However, their size, weight, and power capacity limit the processing capabilities available onboard. In this paper, we describe an approach to state estimation that helps to alleviate this problem. By using an improved dynamic model we show how to more accurately estimate the aircraft states than can be done with the traditional approach of integrating IMU measurements. The estimation is done with relatively infrequent corrections from accelerometers (40Hz) and …

Differential Flatness Based Control Of A Rotorcraft For Aggressive Maneuvers, Timothy Mclain, Randal W. Beard, Robert C. Leishman, Jeffrey L. Ferrin

Faculty Publications

We propose a new method to control a multi-rotor aerial vehicle. We show that the system dynamics are differentially flat. We utilize the differential flatness of the system to provide a feed forward input. The system model derived allows for arbitrary changes in yaw and is not limited to small roll and pitch angles. We demonstrate in hardware the ability to follow a highly maneuverable path while tracking a time-varying heading command.

Compressibility Effects Of Extended Formation Flight, Andrew Ning, Ilan Kroo

Faculty Publications

Aircraft flown in formations may realize significant reductions in induced drag by flying in regions of wake upwash. However, most transports fly at transonic speeds and compressibility effects in formation flight are not well understood. This study uses an Euler solver to analyze the inviscid aerodynamic forces and moments of transonic wing/body configurations flying in a 2-aircraft formation. We consider formations with large streamwise separation distances (10-50 wingspans) in an arrangement we term extended formation flight. Compressibility-related drag penalties in formation flight may be eliminated by slowing 2-3% below the nominal out-of-formation drag divergence Mach number, at fixed lift coefficient …

Dynamics Of A Partially Fluid-Filled Sphere, Jeff Hendricks, Taylor W. Killian, Robert A. Klaus, Nick Smith, Tadd T. Truscott

Faculty Publications

We introduce a study on the slosh dynamics of a partially filled elastic sphere. Currently the physical design of fluid-filled containers utilizes clever construction and machinery to mitigate sloshing motions. There are numerous cases that have been observed but we focus on the impact of a sphere under free fall with an initially undisturbed free surface. The study focuses on measurement and simulation of the force distribution between the fluid and the sphere through the use of high-speed imaging and finite element analysis. Using the cavity shape data, a potential flow numerical model is developed that predicts the unsteady forces. …

Aerodynamic Performance Of Extended Formation Flight, Andrew Ning, Tristan Flanzer, Ilan Kroo

Faculty Publications

Close formation flight is of limited practicality for commercial aviation. Our concept of extended formation flight takes advantage of the persistence of cruise wakes by extending the streamwise spacing between aircraft in a formation. This allows the aircraft to fly at safe separation distances from each other, while still benefiting from the upwash of the upstream wake(s). In this paper we are interested in estimating the performance of these extended formations, and estimating some of the effects that limit the longitudinal extent of the formation. We consider the effects of wake rollup, vortex decay, vortex instabilities, vortex motion, and atmospheric …

A 3-D Chain Algorithm With Pseudo-Rigid-Body Model Elements, Robert Parley Chase, Robert H. Todd, Larry L. Howell, Spencer P. Magleby

Faculty Publications

A chain algorithm element is created from pseudo-rigid-body segments and used in a chain calculation that accurately predicts the force deflection relationship of beams with large 3-D deflections. Each chain element is made up of three pseudo-rigid-body models superimposed on each other acting orthogonally in relation to each other. The chain algorithm can predict large displacements and the force-deflection relationship of lateral torsional buckled beams significantly faster than the finite element method. This approach is not intended to compete with finite element analysis, but rather is a supplement tool that may prove particularly useful in the early phases of design …

Self Assembly In Additive Manufacturing: Opportunities And Obstacles, Nathan B. Crane, J. Tuckerman, G. N. Nielson

Faculty Publications

Purpose

Additive manufacturing offers substantial flexibility in shape, but much less flexibility in materials and functionality—particularly at small size scales. A system for automatically incorporating microscale components would enable the fabrication of objects with more functionality. This paper considers the potential of self assembly to serve as an automated programmable integration method. In particular, it addresses the ability of random self assembly processes to successfully assemble objects with high performance despite the possibility of assembly errors.

Methodology

A self-assembled thermoelectric system is taken as a sample system. The performance expectations for these systems are then predicted using modified one-dimensional models …