Thesis (M.S.)--Ohio University, March, 1992. / Title from PDF t.p.

This study presents a new analytical controller design strategy for the teleoperation of mechanical manipulators aboard the U.S. space station. This controller design strategy emphasizes on the stability of a closed-loop control system involving time delay. Simplified dynamic equations of the Stanford arm are considered as the manipulator model. A local linearizing and decoupling control algorithm is applied to linearize and decouple the dynamic equations. Once the linear form of the manipulator is obtained, a model prediction control loop is constructed and implemented as a digital controller to provide the predictive states information, and a particular model reduction method is applied to yield a reduced-order digital controller. This reduced-order digital controller is a highly self-tuned controller which can control the closed-loop system with time delay by following a specified performance.

Control of high-speed, light-weight robotic manipulators is a challenge because of their special dynamic characteristics. In this work, a two-stage control algorithm for the position control of flexible manipulators is proposed. First, the more complex, flexible robot system is replaced by a simplified hypothetical rigid body system (HRRA) with off-line trajectory planning. This reduces the complexity of the controller design for the flexible robotic arm. A parameter-optimization approach was adopted to minimize the difference between these two models in this stage. Also, a comparison of computational efficiency is made among the methods of calculus-of-variations, dynamic-programming, and the proposed parameter-optimization. At the second stage, simple linear state feedback controllers, based on the simplified hypothetical rigid body model, are proposed to control the actual robotic system. With the feedback gains selected properly by the pole-placement and linear quadratic methods, the results show satisfactory achievement of the motion objectives. The algorithm is implemented for a two-link rigid/flexible robotic arm, and the results indicate that the procedure is capable of providing effective control with much simpler computational requirements than those of procedures published previously. / Graduation date: 1992

The amidohydrolase superfamily is a functionally diverse group of enzymes found in every organism sequenced to date. The landmark for this superfamily is the conservation of a (beta/alpha)8-barrel structural fold. Isoaspartyl dipeptidase (IAD) from Escherichia coli catalyzes the hydrolytic cleavage of beta-aspartyl dipeptides. Structural studies of the wild-type enzyme demonstrate that the active site consists of a binuclear metal center. Bell-shaped pH-rate profiles are observed for all four metal-substituted forms of the wild-type enzyme and the site-directed mutants, E77Q and Y137F. Structural analysis of IAD with the bound substrate and site-directed mutagenesis shows the importance of the side chains of residues Glu-77, Tyr-137, Arg-169, Arg-233, Asp- 285, and Ser-289 in the substrate binding and hydrolysis. The reaction mechanism for the hydrolysis of dipeptides by IAD is initiated by the polarization of the amide bond via complexation to the beta-metal and the hydrogen bond to Tyr-137. Asp-385 participates in the activation of the bridging hydroxide for nucleophilic attack at the peptide carbon center. The lately protonated Asp-285 donates the proton to the alpha-amino group of the leaving group, causing the collapse of the tetrahedral intermediate and cleavage of the carbon-nitrogen bond. N-formimino-L-glutamate iminohydrolase (HutF) from Pseudomonas aeruginosa acts in the deimination of the fourth intermediate of the histidine degradation pathway, N-formimino-L-glutamate. An amino acid sequence alignment between HutF and other members of the amidohydrolase superfamily containing mononuclear metal centers suggests that the residues Glu-235, His-269, and Asp-320 are involved in substrate binding and deimination. Site-directed mutagenesis of Glu-235, His-269, and Asp-320, in conjunction with the analysis of the four metalsubstituted enzyme forms and pH-rate profiles provides valuable information toward the proposal of a mechanism for deimination of N-formimino-L-glutamate by HutF. This information suggests that the reaction is initiated by the activation of the hydrolytic water through base catalysis via His-269. The enhanced nucleophile attacks the formimino carbon center. In a concerted reaction, Asp-320 deprotonates the hydroxide nucleophile, and His-269 donates a proton to the terminal amino of the iminium group resulting in the collapse of the tetrahedral intermediate, the cleavage of the carbon-nitrogen bond and the release of the products.

Thesis (M.S.)--University of Wyoming, 2001. / The compression spring design calculator is available on the World Wide Web. Includes bibliographical references (leaf 50).

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