In this thesis the question of stabilization of perturbed (or uncertain) infinite dimensional linear systems is considered. First, we identify the class of perturbations for which the system remains controllable thereby stabilizable by the same feedback law as for the nominal system. That is, sufficient conditions are presented that guarantee stabilizability of the perturbed system given that the unperturbed system has similar properties. Secondly, we present a methodology for designing feedback controllers such that the feedback system is stable. It is shown that exponential stability can be achieved by choice of suitable additional state feedback controls even in the presence of unbounded and nonlinear perturbations. Both deterministic and stochastic systems are considered. Finally, we apply these stabilization results to a simplified SCOLE model proposed by NASA. Numerical simulations are carried out to illustrate the impact of perturbations on the performance of the space structures and the effectiveness of the stabilizing control.

An original model-based tactile 3-D object recognition system is presented. The development of this system was motivated by the need for a "blind" back-up solution to maintain the object recognition capability of the Space Shuttle robot manipulator when the sun light blinds the video-cameras normally used for object recognition. Tactile object recognition requires the identification of the explored object as well as the recovery of its 3-D position and orientation. Such a complex task calls for a robotic tactile sensing system whose parameters (spatial resolution, probing compliance, tactile image processing) are beyond those usually offered by the emergent tactile sensing technology. The development of the tactile sensing system described in this thesis has resulted in a number of contributions: (i) novel tab-shaped elastic overlay which reduces the cross-talk errors in the tactile sensor, (ii) instrumented passive compliant wrist for more efficient object exploration, and (iii) 2-D correlation method for the integration of the local tactile images in a global image of the explored object surface. The original model-based tactile object recognition paradigm in this thesis can be summarized as follows: "Given a set of 3-D objects having their surfaces Braille-like embossed with terms of a Pseudo-Random Array (PRA) for which is a priori known how the unfolded faces of geometrical models of these objects are mapped into the PRA plane, and given the tactile image of the explored object surfaces, determine the identity, position, and orientation of that object." Tactile object recognition is thus reduced to the recognition of a small set of symbols embossed on object surfaces. The use of multi-valued (instead of the usual binary) pseudo-random encoding allows to reduce the number of embossed symbols which actually are needed to recognized in the tactile image. An original contribution is made by the development of a Pseudo-Random Multi-Valued Product Array (PRMVPA) encoding and related pseudo-random/natural code conversion algorithm. While it is inherently limited to a given set of embossed objects, the described "blind" method allows for a simpler and faster 3-D object recognition using solely tactile sensing. Such an object recognition method has potential applications in controlled environments such as the Space Shuttle, nuclear stations, underwater maintenance of the oil platforms and pipelines.

Abstract not available.

The formation and development of a vortex generated by a wing with a NACA0012 airfoil section in the presence of grid-generated turbulence was studied at Reynolds numbers 29000 in a water tunnel and 240000 in a wind tunnel. Flow visualization indicated that the free-stream turbulence did not significantly affect the large-scale features of the vortex during its formation, however, it resulted in an increase in the turbulence within the vortex as well as an increase in the wandering motion of the vortex. Extensive single-point and two-point, three-component hot-wire anemometry.measurements were conducted for the no-grid case and four cases using two different grids. Time-averaged statistics were found to be significantly influenced by wandering of the vortex position. Quantitative analysis of vortex wandering showed a significant increase in its amplitude with increasing free-stream turbulence. The radial profile of the circumferential velocity with respect to the wandering vortex axis was reconstructed using two-point measurements. The rate of decay of the peak circumferential velocity was found to increase with increasing free-stream turbulence, but the radial location at which it occurred did not change significantly. Analysis of the velocity signals indicated that the turbulent eddies from the wing's wake and the grid turbulence tend to wrap around the vortex core.

Incompressible flow past a 1:48 scale model of the CF-18 fighter aircraft was studied in a water tunnel at the University of Ottawa. Flow visualization records were obtained for flow around different stores, the Leading Edge Extension (LEX) vortex, and the forebody vortex, at various angles of attack. The stores were mostly studied in the low angle of attack range between $\alpha$ = $-$1$\sp\circ$ and $\alpha$ = 5$\sp\circ$. At these angles, their effect on the flow was local. Decreasing the spacing between stores caused the flow to slow down considerably because of the interaction of the separated flow on the wing with the boundary layers of the individual stores. The LEX vortex became stronger as the angle of attack was increased, and the location of its breakdown moved upstream. The breakdown location showed good correlation with results of other model and full-scale studies. The forebody vortex was weaker than the LEX vortex, and was consistently drawn towards the LEX until the two vortices began interacting. The variation of the LEX vortex bursting location with angle of attack is only weakly sensitive to Reynolds number and, therefore, the water tunnel tests can provide a good simulation of full-scale flow characteristics. On the other hand, flow characteristics near surfaces change substantially with increasing Reynolds number, so that the water tunnel results in such regions must be viewed with reservation, when considering their relevance to the high Reynolds number flow around the aircraft. (Abstract shortened by UMI.)

Intensive research efforts are currently directed toward special robotic applications. One of the largest international projects with a focus on this research is the Space Station Freedom. Canada's contribution to this project is a Mobile Servicing System (MSS). This system will be used for assembly and maintenance of the space station. The MSS will consist of a long single arm with a dual-arm robot attached to its end. They require a hierarchical controller to coordinate the arms while executing such tasks as trajectory generation, arm-arm collision avoidance, arm-obstacle collision avoidance, and the manipulation of solid and flexible body payloads. This thesis presents the research work for building a functional hardware and software model of a test-bed dual-arm robot with flexible object handling capabilities using impedance control. It addresses issues such as input-output linearization, perturbation observer, sensor fusion, and provides the experimental results of a dual-arm manipulator using the proposed techniques. To date, no work exists which shows that the application of a dual-arm robot handling flexible payloads in space applications is possible.

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