+publisher:"University of Colorado" +contributor:("Daniel Moorer")

University of Colorado

1. Seubert, Carl. One-Dimensional Spacecraft Formation Flight Testbed for Terrestrial Charged Relative Motion Experiments.

Degree: PhD, Aerospace Engineering Sciences, 2011, University of Colorado

URL: https://scholar.colorado.edu/asen_gradetds/38

► Spacecraft operating in a desired formation offers an abundance of attractive mission capabilities. One proposed method of controlling a close formation of spacecraft is… (more)

▼ Spacecraft operating in a desired formation offers an abundance of attractive mission capabilities. One proposed method of controlling a close formation of spacecraft is with Coulomb (electrostatic) forces. The Coulomb formation flight idea utilizes charge emission to drive the spacecraft to kilovolt-level potentials and generate adjustable, micronewton- to millinewton-level Coulomb forces for relative position control. In order to advance the prospects of the Coulomb formation flight concept, this dissertation presents the design and implementation of a unique one-dimensional testbed. The disturbances of the testbed are identified and reduced below 1 mN. This noise level offers a near-frictionless platform that is used to perform relative motion actuation with electrostatics in a terrestrial atmospheric environment. Potentials up to 30 kV are used to actuate a cart over a translational range of motion of 40 cm. A challenge to both theoretical and hardware implemented electrostatic actuation developments is correctly modeling the forces between finite charged bodies, outside a vacuum. To remedy this, studies of Earth orbit plasmas and Coulomb force theory is used to derive and propose a model of the Coulomb force between finite spheres in close proximity, in a plasma. This plasma force model is then used as a basis for a candidate terrestrial force model. The plasma-like parameters of this terrestrial model are estimated using charged motion data from fixed-potential, single-direction experiments on the testbed. The testbed is advanced to the level of autonomous feedback position control using solely Coulomb force actuation. This allows relative motion repositioning on a flat and level track as well as an inclined track that mimics the dynamics of two charged spacecraft that are aligned with the principal orbit axis. This controlled motion is accurately predicted with simulations using the terrestrial force model. This demonstrates similarities between the partial charge shielding of space-based plasmas to the electrostatic screening in the laboratory atmosphere. Advisors/Committee Members: Hanspeter Schaub, Penina Axelrad, Daniel Moorer.

Subjects/Keywords: Coulomb; formation; modeling; plasma; spacecraft; testbed; Aerospace Engineering

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Seubert, C. (2011). One-Dimensional Spacecraft Formation Flight Testbed for Terrestrial Charged Relative Motion Experiments. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/asen_gradetds/38

Chicago Manual of Style (16^th Edition):

Seubert, Carl. “One-Dimensional Spacecraft Formation Flight Testbed for Terrestrial Charged Relative Motion Experiments.” 2011. Doctoral Dissertation, University of Colorado. Accessed March 07, 2021. https://scholar.colorado.edu/asen_gradetds/38.

MLA Handbook (7^th Edition):

Seubert, Carl. “One-Dimensional Spacecraft Formation Flight Testbed for Terrestrial Charged Relative Motion Experiments.” 2011. Web. 07 Mar 2021.

Vancouver:

Seubert C. One-Dimensional Spacecraft Formation Flight Testbed for Terrestrial Charged Relative Motion Experiments. [Internet] [Doctoral dissertation]. University of Colorado; 2011. [cited 2021 Mar 07]. Available from: https://scholar.colorado.edu/asen_gradetds/38.

Council of Science Editors:

Seubert C. One-Dimensional Spacecraft Formation Flight Testbed for Terrestrial Charged Relative Motion Experiments. [Doctoral Dissertation]. University of Colorado; 2011. Available from: https://scholar.colorado.edu/asen_gradetds/38

University of Colorado

2. Abdel-Samad, Chadi S. Optimization and Control of an Active Helmet Design for Head Injury Prevention.

Degree: PhD, Electrical, Computer & Energy Engineering, 2015, University of Colorado

URL: https://scholar.colorado.edu/ecen_gradetds/114

► Thousands of mild traumatic brain injuries (mBTIs) occur in US football each year. In some instances, injuries are quite serious and life-threatening. New NFL… (more)

Subjects/Keywords: Airbag; Concussion; Football; Protection; Biomechanics; Biomedical Engineering and Bioengineering; Robotics

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Abdel-Samad, C. S. (2015). Optimization and Control of an Active Helmet Design for Head Injury Prevention. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/ecen_gradetds/114

Chicago Manual of Style (16^th Edition):

Abdel-Samad, Chadi S. “Optimization and Control of an Active Helmet Design for Head Injury Prevention.” 2015. Doctoral Dissertation, University of Colorado. Accessed March 07, 2021. https://scholar.colorado.edu/ecen_gradetds/114.

MLA Handbook (7^th Edition):

Abdel-Samad, Chadi S. “Optimization and Control of an Active Helmet Design for Head Injury Prevention.” 2015. Web. 07 Mar 2021.

Vancouver:

Abdel-Samad CS. Optimization and Control of an Active Helmet Design for Head Injury Prevention. [Internet] [Doctoral dissertation]. University of Colorado; 2015. [cited 2021 Mar 07]. Available from: https://scholar.colorado.edu/ecen_gradetds/114.

Council of Science Editors:

Abdel-Samad CS. Optimization and Control of an Active Helmet Design for Head Injury Prevention. [Doctoral Dissertation]. University of Colorado; 2015. Available from: https://scholar.colorado.edu/ecen_gradetds/114

University of Colorado

3. Stiles, Laura Ann. Electrostatic In ation of Membrane Space Structures.

Degree: PhD, Aerospace Engineering Sciences, 2013, University of Colorado

URL: https://scholar.colorado.edu/asen_gradetds/92

► Membrane space structures provide a lightweight and cost effective alternative to traditional mechanical systems. The low-mass and high deployed-to-stored volume ratios allow for larger… (more)

▼ Membrane space structures provide a lightweight and cost effective alternative to traditional mechanical systems. The low-mass and high deployed-to-stored volume ratios allow for larger structures to be launched, expanding on-orbit science and technology capabilities. This research explores a novel method for deployment of membrane space structures using electrostatic pressure as the inflation mechanism. Applying electric charge to a layered gossamer structure provides an inflationary pressure due to the repulsive electrostatic forces between the charged layers. The electrostatic inflation of membrane structures (EIMS) concept is particularly applicable to non-precision structures such as sunshields or drag de-orbiting devices. This research addresses three fundamental topics: necessary conditions for EIMS in a vacuum, necessary conditions for EIMS in a plasma, and charging methods. Vacuum demonstrations show that less than 10 kiloVolts are required for electrostatic inflation of membrane structures in 1-g. On-orbit perturbation forces can be much smaller, suggesting feasible voltage requirements. Numerical simulation enables a relationship between required inflation pressure (to offset disturbances) and voltage. 100's of Volts are required for inflation in geosynchronous orbits (GEO) and a few kiloVolts in low Earth orbit (LEO). While GEO plasma has a small impact on the EIMS performance, Debye shielding at LEO reduces the electrostatic pressure. The classic Debye shielding prediction is far worse than actual shielding, raising the `effective' Debye length to the meter scale in LEO, suggesting feasibility for EIMS in LEO. Charged particle emission and remote charging methods are explored as inflation mechanisms. Secondary electron emission characteristics of EIMS materials were determined experimentally. Nonlinear fits to the Sternglass curve determined a maximum yield of 1.83 at 433 eV for Aluminized Kapton and a maximum yield of 1.78 at 511 eV for Aluminized Mylar. Remote charging was demonstrated to -500 V with a 5 keV electron beam. Charge emission power levels are below 1 Watt in GEO and from 10's of Watt to a kiloWatt in LEO. Advisors/Committee Members: Hanspeter Schaub, Zoltan Sternovsky, Kurt Maute, Dejan Filipovic, Daniel Moorer.

Subjects/Keywords: Deployable Spacecraft; Inflatable Structures; Plasma Physics; Spacecraft Charging; Aerospace Engineering

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Stiles, L. A. (2013). Electrostatic In ation of Membrane Space Structures. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/asen_gradetds/92

Chicago Manual of Style (16^th Edition):

Stiles, Laura Ann. “Electrostatic In ation of Membrane Space Structures.” 2013. Doctoral Dissertation, University of Colorado. Accessed March 07, 2021. https://scholar.colorado.edu/asen_gradetds/92.

MLA Handbook (7^th Edition):

Stiles, Laura Ann. “Electrostatic In ation of Membrane Space Structures.” 2013. Web. 07 Mar 2021.

Vancouver:

Stiles LA. Electrostatic In ation of Membrane Space Structures. [Internet] [Doctoral dissertation]. University of Colorado; 2013. [cited 2021 Mar 07]. Available from: https://scholar.colorado.edu/asen_gradetds/92.

Council of Science Editors:

Stiles LA. Electrostatic In ation of Membrane Space Structures. [Doctoral Dissertation]. University of Colorado; 2013. Available from: https://scholar.colorado.edu/asen_gradetds/92

University of Colorado

4. Stevenson, Daan. Remote Spacecraft Attitude Control by Coulomb Charging.

Degree: PhD, Aerospace Engineering Sciences, 2015, University of Colorado

URL: https://scholar.colorado.edu/asen_gradetds/94

► The possibility of inter-spacecraft collisions is a serious concern at Geosynchronous altitudes, where many high-value assets operate in proximity to countless debris objects whose… (more)

▼ The possibility of inter-spacecraft collisions is a serious concern at Geosynchronous altitudes, where many high-value assets operate in proximity to countless debris objects whose orbits experience no natural means of decay. The ability to rendezvous with these derelict satellites would enable active debris removal by servicing or repositioning missions, but docking procedures are generally inhibited by the large rotational momenta of uncontrolled satellites. Therefore, a contactless means of reducing the rotation rate of objects in the space environment is desired. This dissertation investigates the viability of Coulomb charging to achieve such remote spacecraft attitude control. If a servicing craft imposes absolute electric potentials on a nearby nonspherical debris object, it will impart electrostatic torques that can be used to gradually arrest the object's rotation. In order to simulate the relative motion of charged spacecraft with complex geometries, accurate but rapid knowledge of the Coulomb interactions is required. To this end, a new electrostatic force model called the Multi-Sphere Method (MSM) is developed. All aspects of the Coulomb de-spin concept are extensively analyzed and simulated using a system with simplified geometries and one dimensional rotation. First, appropriate control algorithms are developed to ensure that the nonlinear Coulomb torques arrest the rotation with guaranteed stability. Moreover, the complex interaction of the spacecraft with the plasma environment and charge control beams is modeled to determine what hardware requirements are necessary to achieve the desired electric potential levels. Lastly, the attitude dynamics and feedback control development is validated experimentally using a scaled down terrestrial testbed. High voltage power supplies control the potential on two nearby conductors, a stationary sphere and a freely rotating cylinder. The nonlinear feedback control algorithms developed above are implemented to achieve rotation rate and absolute attitude control. Collectively, these studies decisively validate the feasibility of Coulomb charging for remote spacecraft attitude control. Advisors/Committee Members: Hanspeter Schaub, Webster Cash, Brandon Jones, Daniel Moorer, Zoltan Sternovsky.

Subjects/Keywords: electrostatic modeling; high voltage experimentation; spacecraft attitude control; spacecraft charging; Multi-Vehicle Systems and Air Traffic Control; Navigation, Guidance, Control and Dynamics; Space Vehicles

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Stevenson, D. (2015). Remote Spacecraft Attitude Control by Coulomb Charging. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/asen_gradetds/94

Chicago Manual of Style (16^th Edition):

Stevenson, Daan. “Remote Spacecraft Attitude Control by Coulomb Charging.” 2015. Doctoral Dissertation, University of Colorado. Accessed March 07, 2021. https://scholar.colorado.edu/asen_gradetds/94.

MLA Handbook (7^th Edition):

Stevenson, Daan. “Remote Spacecraft Attitude Control by Coulomb Charging.” 2015. Web. 07 Mar 2021.

Vancouver:

Stevenson D. Remote Spacecraft Attitude Control by Coulomb Charging. [Internet] [Doctoral dissertation]. University of Colorado; 2015. [cited 2021 Mar 07]. Available from: https://scholar.colorado.edu/asen_gradetds/94.

Council of Science Editors:

Stevenson D. Remote Spacecraft Attitude Control by Coulomb Charging. [Doctoral Dissertation]. University of Colorado; 2015. Available from: https://scholar.colorado.edu/asen_gradetds/94

		in
And / Or
		in
And / Or
		in
And / Or
		in

Open Access Theses and Dissertations