NASA Scientific and Technical Aerospace Reports

20060001813 Michigan Univ., Ann Arbor, MI USA
Diagnostic Testing and NIKE Experiments
Drake, R. P.; Harding, Eric C.; Aug. 1, 2005; 14 pp.; In English; Original contains color illustrations
Contract(s)/Grant(s): N00173-04-1-G905
Report No.(s): AD-A440295; No Copyright; Avail.: CASI: A03, Hardcopy
Under this contract we have developed a Monte Carlo model of microchannel plate performance, made measurements for
comparison with the model, and identified potential strategies for improving the performance of microchannel plates in analog
imaging applications. This has prepared us to address the optimization of x-ray framing cameras for NRL applications and
long-term possibilities for improvements in performance. In addition, we participated in work at NIKE and gained experience
relevant to working in the NIKE environment.
DTIC
Gas Lasers; Laser Plasmas; Microchannel Plates
20060001823 Illinois Univ. at Urbana-Champaign, Urbana, IL USA
Plume Expansion and Ionization in a Micro Laser Plasma Thruster
Reilly, Michael P.; Miley, George H.; Hargus, William A., Jr; Jun. 1, 2005; 14 pp.; In English
Contract(s)/Grant(s): Proj-2308
Report No.(s): AD-A440312; No Copyright; Avail.: CASI: A03, Hardcopy
Ion density measurements have been performed on the plasma generated by an ablative diode laser thruster using a
negatively biased flat plate probe. The biased probe data was coupled with measurement of the ablation crater through use of
a scanning electron microscope (SEM). The SEM was used to analyze the post-pulse ablation spots to determine the volume
of fuel ablated. The micro-laser plasma thruster (micro-LPT) discussed here ablates a target material through the back surface
by focusing the laser through a transparent substrate in a process typically referred to as Transmissive mode (T-mode) ablation.
The target materials investigated were polyvinyl chloride (PVC) and glycidyl azide polymer (GAP), while the substrates used
were cellulose acetate and Kapton(Tradename). Peak ion densities for a GAP (target)/acetate (substrate) were found to be
1.6x10(exp 7)/cu cm, while for GAP/kapton and PVC/acetate the peak ion densities were 4.5x10(exp 7)/cu cm and 7.9x10(exp
9)/cu cm respectively. Although these corresponded to low ionization fractions calculated from the observed mass loss, the
results indicate there are ways to improve the ionization fraction and in turn increase the specific impulse.
DTIC
Ablation; Ionization; Laser Applications; Laser Plasmas; Lasers; Plumes; Thermal Expansion
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MECHANICAL ENGINEERING
Includes mechanical devices and equipment; machine elements and processes. For cases where the application of a device or the host
vehicle is emphasized see also the specific category where the application or vehicle is treated. For robotics see 63 Cybernetics,
Artificial Intelligence, and Robotics; and 54 Man/System Technology and Life Support.
20060001254 Southern Taiwan Univ. of Technology, Tainan, Taiwan, Province of China
A Robust Bounded Control for an Autonomous Vehicle Subject to Combined Wheel Slip Constraint
Peng, Shou-Tao; Sheu, Jer-Jia; Chang, Chau-Chin; Journal of the Chinese Institute of Engineers; Vol. 28, No. 6; October 2005,
pp. 935-948; In English; See also 20060001246
Contract(s)/Grant(s): NSC-93-2218-E-218-006; Copyright; Avail.: Other Sources
This paper presents a robust bounded control that prevents wheel skidding for an autonomous 4WS4WD vehicle under
uncertain tire/road conditions with aerodynamic drag. Constraints on combined wheel slip are incorporated, a priori, in design
to prevent skidding. A robust low-and-high gain technique is used to suppress the tracking error, and to enhance the utilization
of the limited wheel slip. Simulation shows that, under uncertain tirehoad conditions, with aerodynamic drag, the proposed
control scheme can effectively limit the combined wheel slip, and it achieves the goal of path tracking. Moreover, the control
inputs of wheel torque and wheel steering are coordinated well during vehicle cornering.
Author
Aerodynamic Drag; Autonomy; Skidding; Vehicle Wheels; Tires
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