1,483 research outputs found
Optimal Control of an Uninhabited Loyal Wingman
As researchers strive to achieve autonomy in systems, many believe the goal is not that machines should attain full autonomy, but rather to obtain the right level of autonomy for an appropriate man-machine interaction. A common phrase for this interaction is manned-unmanned teaming (MUM-T), a subset of which, for unmanned aerial vehicles, is the concept of the loyal wingman. This work demonstrates the use of optimal control and stochastic estimation techniques as an autonomous near real-time dynamic route planner for the DoD concept of the loyal wingman. First, the optimal control problem is formulated for a static threat environment and a hybrid numerical method is demonstrated. The optimal control problem is transcribed to a nonlinear program using direct orthogonal collocation, and a heuristic particle swarm optimization algorithm is used to supply an initial guess to the gradient-based nonlinear programming solver. Next, a dynamic and measurement update model and Kalman filter estimating tool is used to solve the loyal wingman optimal control problem in the presence of moving, stochastic threats. Finally, an algorithm is written to determine if and when the loyal wingman should dynamically re-plan the trajectory based on a critical distance metric which uses speed and stochastics of the moving threat as well as relative distance and angle of approach of the loyal wingman to the threat. These techniques are demonstrated through simulation for computing the global outer-loop optimal path for a minimum time rendezvous with a manned lead while avoiding static as well as moving, non-deterministic threats, then updating the global outer-loop optimal path based on changes in the threat mission environment. Results demonstrate a methodology for rapidly computing an optimal solution to the loyal wingman optimal control problem
2006 NASA Range Safety Annual Report
Throughout 2006, Range Safety was involved in a number of exciting and challenging activities and events, from developing, implementing, and supporting Range Safety policies and procedures-such as the Space Shuttle Launch and Landing Plans, the Range Safety Variance Process, and the Expendable Launch Vehicle Safety Program procedures-to evaluating new technologies. Range Safety training development is almost complete with the last course scheduled to go on line in mid-2007. Range Safety representatives took part in a number of panels and councils, including the newly formed Launch Constellation Range Safety Panel, the Range Commanders Council and its subgroups, the Space Shuttle Range Safety Panel, and the unmanned aircraft systems working group. Space based range safety demonstration and certification (formerly STARS) and the autonomous flight safety system were successfully tested. The enhanced flight termination system will be tested in early 2007 and the joint advanced range safety system mission analysis software tool is nearing operational status. New technologies being evaluated included a processor for real-time compensation in long range imaging, automated range surveillance using radio interferometry, and a space based range command and telemetry processor. Next year holds great promise as we continue ensuring safety while pursuing our quest beyond the Moon to Mars
Pilots’ visual scan pattern and attention distribution during the pursuit of a dynamic target
Introduction: The current research is investigating pilots’ visual
scan patterns in order to assess attention distribution during
air-to-air manoeuvers. Method: A total of thirty qualified
mission-ready fighter pilots participated in this research. Eye
movement data were collected by a portable head-mounted eye-tracking
device, combined with a jet fighter simulator. To complete the task,
pilots have to search for, pursue, and lock-on a moving target whilst
performing air-to-air tasks. Results: There were significant
differences in pilots’ saccade duration (msec) in three operating
phases including searching (M=241, SD=332), pursuing (M=311, SD=392),
and lock-on (M=191, SD=226). Also, there were significant differences
in pilots’ pupil sizes (pixel2) of which lock-on phase was the largest
(M=27237, SD=6457), followed by pursuing (M=26232, SD=6070), then
searching (M=25858, SD=6137). Furthermore, there were significant
differences between expert and novice pilots on the percentage of
fixation on the HUD, time spent looking outside the cockpit, and the
performance of situational awareness (SA). Discussion: Experienced
pilots have better SA performance and paid more attention to the HUD
but focused less outside the cockpit when compared with novice pilots.
Furthermore, pilots with better SA performance exhibited a smaller
pupil size during the operational phase of lock-on whilst pursuing
a dynamic target. Understanding pilots’ visual scan patterns and
attention distribution are beneficial to the design of interface
displays in the cockpit and in developing human factors training
syllabi to improve safety of flight operations
An adaptive autopilot design for an uninhabited surface vehicle
An adaptive autopilot design for an uninhabited surface vehicle
Andy SK Annamalai
The work described herein concerns the development of an innovative approach to the
design of autopilot for uninhabited surface vehicles. In order to fulfil the requirements of
autonomous missions, uninhabited surface vehicles must be able to operate with a minimum
of external intervention. Existing strategies are limited by their dependence on a fixed
model of the vessel. Thus, any change in plant dynamics has a non-trivial, deleterious effect
on performance. This thesis presents an approach based on an adaptive model predictive
control that is capable of retaining full functionality even in the face of sudden changes in
dynamics.
In the first part of this work recent developments in the field of uninhabited surface vehicles
and trends in marine control are discussed. Historical developments and different strategies
for model predictive control as applicable to surface vehicles are also explored. This thesis
also presents innovative work done to improve the hardware on existing Springer
uninhabited surface vehicle to serve as an effective test and research platform. Advanced
controllers such as a model predictive controller are reliant on the accuracy of the model to
accomplish the missions successfully. Hence, different techniques to obtain the model of
Springer are investigated. Data obtained from experiments at Roadford Reservoir, United
Kingdom are utilised to derive a generalised model of Springer by employing an innovative
hybrid modelling technique that incorporates the different forward speeds and variable
payload on-board the vehicle. Waypoint line of sight guidance provides the reference
trajectory essential to complete missions successfully.
The performances of traditional autopilots such as proportional integral and derivative
controllers when applied to Springer are analysed. Autopilots based on modern controllers
such as linear quadratic Gaussian and its innovative variants are integrated with the
navigation and guidance systems on-board Springer. The modified linear quadratic
Gaussian is obtained by combining various state estimators based on the Interval Kalman
filter and the weighted Interval Kalman filter.
Change in system dynamics is a challenge faced by uninhabited surface vehicles that result
in erroneous autopilot behaviour. To overcome this challenge different adaptive algorithms
are analysed and an innovative, adaptive autopilot based on model predictive control is
designed. The acronym ‘aMPC’ is coined to refer to adaptive model predictive control that
is obtained by combining the advances made to weighted least squares during this research
and is used in conjunction with model predictive control. Successful experimentation is
undertaken to validate the performance and autonomous mission capabilities of the adaptive
autopilot despite change in system dynamics.EPSRC (Engineering and Physical Sciences Research Council
Survey of the Status of Small and Very Small Missiles
The project ‘Preventive Arms Control for Small and Very Small Armed Aircraft and Missiles’ investigates the properties of ever smaller aircraft and missiles. This project report no. 2 covers the status of missiles worldwide. Small and very small missiles are defined by diameter: below 69 mm and up to 40 mm, respectively. After an explanation of missile classes and typical properties, a short introduction into rocket propulsion and aerodynamics is given. A technical overview describes the components of a missile. A few example types are shown and potential military uses are discussed. The worldwide survey has resulted in a database that contains 50 types from 17 countries. The publicly available properties are given in 24 categories. Statistical evaluations cover several key parameters
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