A crucial component of instructional design for simulation-based training systems involves optimizing the presentation of complex material in order to maximize knowledge acquisition and application. One approach toward facilitating the learning of this complex information is to instantiate instructional strategies within the training systems themselves. However, there are few established guidelines in place which are meant specifically for real-time guidance strategies within simulation-based environments. Consequently, this study aims to apply findings from the literature on instructional information presentation to drive decisions for how to most effectively provide real-time feedback during training of simulated decision-making tasks. Research has shown that presenting text information in an auditory mode during direct instruction of operational tasks enhances learning and reduces the probability of learners experiencing cognitive overload. Similar effects have been found regarding the presentation modality of feedback during operational tasks. In the current study, this principle was extended by comparing text versus verbal real-time feedback presentation during learning of higher-level cognitive skills in a virtual environment. Participants were instructed on how to perform a simulated decisionmaking task, while receiving text, verbal or no instructional feedback in real-time, based on their performance. Participants then completed an assessment scenario in which no feedback was provided to any group. It was hypothesized that a linear relationship would exist across each of the three conditions, with the verbal group making the best decisions, followed by the text group, and then by the control group. Additionally, reduced cognitive load was expected throughout the instructional process for those receiving verbal feedback prompts compared to those receiving text prompts and the control. Analyses revealed several significant linear trends across iv conditions regarding measures of knowledge acquisition and application. The results provide support for the hypothesis that verbal real-time feedback is more effective than text during training of primarily visual tasks for the acquisition of higher-order cognitive skills such as decision making. There were no significant linear trends regarding the amount of cognitive load subjectively reported during training and assessment. The results of this study indicate that instructional systems intended to train primarily visual tasks should present real-time feedback in verbal rather than text form.

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A root locus graphics routine was written in Turbo Pascal for the analysis and design of a linearized dual tank control system. The routine is a subprogram to be incorporated with an editor written by L. Fadden. This editor allows for the saving and changing of parameters to the system. The dual tank system is a good example for classical feedback control analysis. A brief description of the process and system is presented. The system may be described by linearized differential and algebraic equations. From these, a characteristic equation is derived, which gives rise to the root locus. The root locus is a plot of the poles of the closed loop system. Poles or roots of the characteristic equation are found using the Lin-Bairstow algorithm. This method may be used to solve for the zeroes of an nth degree polynomial. The root locus plotter was exercised by attempting to optimally tune the system’s controller. Corroboration of the results was provided by step response plots from the TUTSIM simulation program. Minor modifications allow the root locus plotter to run without the editor. Graphics subroutines are provided by the Turbo Graphix Toolbox. When run under the editor, the plotter is one interactive design module of the dual tank system analysis and design program. The subprogram was designed principally for user ease, error checking, and effective graphics.

A model (NONLINRK) was developed for a closed tank system under feedback control by an ideal proportional-integral-derivative controller. Under servo action the fluid level in the tank is altered from its equilibrium set point. Under regulatory action the feed pressure to the inlet valve and/or the outlet valve percentage opening are varied from equilibrium settings. The numerical model uses Gill’s fourth-order Runge-Kutta algorithm to solve the system equation. The equation was made separable by approximating an exponential factor by the tangent at the beginning of each time step in the numerical solution. NONLINRK simulation trials exhibited many characteristics of linear system including unequal offset under proportional control for the setpoint changes equal in magnitude but opposite in sign, harmonics in the response to a sine wave input on fluid level setpoint and bounded response in spite of increased gain settings. In addition, further simulation trials showed the system response converges to that of a linear system for sufficiently small setpoint of load variations. A second model using the modeling language TUTSIM provided corroboration of the results produced by NONLINRK. Proportional and proportional-integral control simulations differed by less than .1% and the models showed the same rates of convergence as the time step was decreased. Under PID control TUTSIM simulations developed severe instabilities, but NONLINRK exhibited the expected trends in the increased ability to react to a ramp function disturbance and the decrease in phase lag in response to a sinusoidal setpoint function.

To reduce complexity of system analysis and control design, simplified models that capture the behavior of interest in the original system can be obtained. These simplified models, called abstractions, can be analyzed more easily than the original complex model. Hierarchies of consistent abstractions can significantly reduce the complexity in determining the reachability properties of nonlinear systems. Such consistent hierarchies of reachability-preserving nonlinear abstractions are considered for the robotic car. Not only can these abstractions be analyzed with respect to some behavior of interest, they can also be used to transfer control design for the complex model to the simplified model. In this work, the abstraction is applied to the car/unicycle system. Working towards control design, it is seen that there are certain classes of trajectories that exist in the rolling disk system that cannot be achieved by the robotic car. In order to account for these cases, the new concepts of traceability and &#949-traceability are introduced. This work also studies the relationship between the evolution of uncertain initial conditions in abstracted control systems. It is shown that a control system abstraction can capture the time evolution of the uncertainty in the original system by an appropriate choice of control input. Abstracted control systems with stochastic initial conditions show the same behavior as systems with deterministic initial conditions. A conservation law is applied to the probability density function (pdf) requiring that the area under it be unity. Application of the conservation law results in a partial differential equation known as the Liouville equation, for which a closed form solution is known. The solution provides the time evolution of the initial pdf which can be followed by the abstracted system. / Ph. D.

Companies which design automation control for the metal rolling industry are faced with a growing demand for systems with higher performance standards than ever before. Along with these demanding specifications is always the problem of system stability at any given speed. A multi-ton rolling stand with uncontrolled oscillations not only destroys the product being rolled but may cause serious damage to the plant and endanger the lives of mill personnel. Therefore stability analysis is critical whether modeling individual mills or analyzing old products and strategies so as to invent better, cheaper control methods. Cost is another major consideration for the firm ordering these systems and the companies which design them. Suppliers are trimming time from design and production schedules wherever possible in order to compete in the world market. It is for these, and other reasons that computer aided stability analysis is so important. The object is to ensure a safe and stable system and yet minimize the time (and therefore cost) needed For design and installation. This paper describes a program (ROOT LOCUS) which was created to fill this need while using the tools and methods readily at hand. It was written for personal computers as these machines are rapidly proving to be cost effective solutions to problems in computing power. / Master of Science

The computer simulation language written in Fortran was used to model the Navy's PHALANX Mount and Antenna Compensation Network. This network is a feedback control system that filters out the effects of surface ship motion on a weapon's response to commands from the ship's fire control center. The network includes a number of non-standard elements that prevent mathematical prediction of its closed-loop response; therefore, a computer model was required to predict the network's output. The computer models were developed, validated and tested with a number of different inputs. The resultant outputs were compared with actual test data taken from a functional PHALANX mount compensation network. / Master of Science