This thesis describes the modelling of electrohydraulic actuation systems of a prototype forestry vehicle, the experimental identification of the dynamic models parameters and control strategies for forestry operations. / The linear graph method is selected to derive comprehensive models of three electrohydraulic actuation subsystems, i.e. the swing, boom and stick subsystems, on the vehicle based on modelling of individual components. A new approach is proposed, then, to integrate rigid-body dynamic models with the actuator dynamic models to result in a complete machine model. / Off-line parameter identification procedures are used, including the least-square method. A series of experiments is performed to obtain numerical values for the parameters involved in the system models. The experimental setups are described in detail and new procedures are explained. The model validation studies show that the mathematical models closely represent the dynamic characteristics of the forestry machine. / The concept of coordinated control in teleoperation is studied. The resolved motion rate control strategy shows superiority over conventional joint-based control in heavy-duty forestry machines. Two inverse Jacobian manipulator control schemes, based on velocity and on position servo schemes, are introduced and evaluated under various operating conditions. The results provide guidelines for the design and implementation of manipulator controllers on a forestry machine.

Recently, robotic technology has begun to play an important role in forestry operations. An important class of forestry machines is comprised of systems equipped with a mobile platform fitted with an articulated arm carrying a tree processing head. The dynamics of such systems are needed for simulation and control purposes. In contrast to conventional industrial manipulators, which are mounted on stationary bases, a mobile manipulator is dynamically coupled with its base. Base compliance, non-linearity and coupled dynamics result in positioning inaccuracies which in turn give rise to control problems. / The dynamics of the FERIC forwarder forestry machine including its compliant tires were developed and implemented symbolically in compact form with the help of an iterative Newton-Euler dynamic formulation. Various models with increasing complexity were derived. Based on a simplified dynamics model, a valve-sizing methodology was developed and used to size hydraulic proportional valves of the machine's actuators. / System parameters have been obtained by various methods, including use of blueprints, weighing, solid modeling and various experiments. A set-point feedforward controller was designed and the machine's responses for various inputs were obtained to analyze the dynamic behavior of the system. Although initial simulations were done in Matlab and Simulink, C programs were developed for increased speed of execution. In addition, techniques to minimize computation time have been developed and applied to result in almost real time simulation.

<p> One of the most difficult endeavors in filamentous algal growth models is predicting the occurrence of sloughing. Algal sloughing can stem from various sources such as from biological or mechanical means. The focus of this study is to investigate the role of fluid shear on the benthic filament mass. This research proposes a method to model the external forces on a benthic filament from the aquatic environment and the internal forces from the movement of the filament mass itself. To accomplish this, three parallel endeavors were pursued. First, a fluid-structure force interaction model was developed that can be applied to a multi-node cylindrical benthic filament model. Second, a finite element modeling approach was used to estimate the internal structural properties based on the filament mass displacement under a specified external force. Third, motion capture techniques from experimental video footage were utilized to provide data for the fluid-structure interaction model and validation of the finite-element model. In laboratory application of this methodology on an experimental sample of mixed-culture filamentous algae, a value of 4.2 MPa was calculated for the internal stress in a filament, a value in close agreement with literature values. This method can provide an in-situ approach to investigate the structural properties of the algal filament in its natural aquatic environment without the use of expensive equipment. </p>

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2008. / Source: Dissertation Abstracts International, Volume: 69-05, Section: B, page: 3122. Adviser: Lei Tian. Includes bibliographical references (leaves 137-148) Available on microfilm from Pro Quest Information and Learning.

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2006. / Source: Dissertation Abstracts International, Volume: 67-07, Section: B, page: 3930. Adviser: Steven R. Eckhoff. Includes bibliographical references (leaves 67-73) Available on microfilm from Pro Quest Information and Learning.

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2006. / Source: Dissertation Abstracts International, Volume: 67-07, Section: B, page: 3515. Adviser: Mike Ellis. Includes bibliographical references. Available on microfilm from Pro Quest Information and Learning.

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2006. / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6546. Adviser: Prasanta K. Kalita. Includes bibliographical references (leaves 229-257) Available on microfilm from Pro Quest Information and Learning.

Soybean oil was extracted from soybean flakes and porous alumina spheres by hexane and isopropanol. Extraction of oil from alumina spheres was normal in terms of appropriate PDE solutions of Fick's second law of diffusion. Extraction of oil from flakes agreed with Fick's second law of diffusion for short extraction times, but deviated significantly from the standard diffusion behavior at long times. In spite of its apparent complexity, the solvent extraction of oil from flaked oilseeds appears to be a linear diffusion process and the diffusivity appears to be independent of oil concentration. This is supported by the following experimental results for soybean flakes: (a) Normalized extraction curves were independent of both oil content in the solid and initial concentration of oil in the extracting solvent; (b) Infusion and extraction occurred at the same rate; (c) Normalized extraction curves for unextracted and previously extracted flakes reinfused with refined oil were virtually identical; and (d) Extraction times for different solvents were inversely proportional to liquid diffusivities of the oil-solvent pairs. Analytical solutions of Fick's second law are presented for batch and differential extraction of slabs and spheres, which account for both internal and external mass transfer resistances. These solutions correlate alumina sphere extraction data well. Soybean flake extraction data were well correlated by two mathematical models. One of these treats the extraction curve as the sum of two or more independent diffusive contributions. The other is a one-parameter empirical model. For short extraction times, experimental data are well correlated by available short-time solutions of the diffusion equation, subject to appropriate initial and boundary conditions. Experimental results for multistage batch extraction of soybean flakes agreed very well with those predicted from superposition of single-stage extraction data by means of Duhamel's theorem. Structural non-uniformity appeared to be the most probable reason for the observed extraction behavior of flaked oilseeds. Other hypotheses have been ruled out based on experimental evidence, including: decreased solubility of the last portions of extracted oil; slow dissolution of oil in the extracting solvent; interaction of oil or solvent with the solid; and concentration-dependent diffusivity.

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