Wong, Tin-Lup

A six-degree-of-freedom model of a vehicle was simulated over different hump profiles with a computer program and the results were verified. The resulting vibration characteristics were analyzed to calculate a discomfort index. The discomfort index considered is the equivalent root mean square acceleration specified by the proposal for the revision of ISO 2631. A parametric study was conducted to find the sensitivity of different hump and vehicular parameters on the ride comfort. The optimal hump parameters were obtained for different limiting speeds. Two field humps were simulated and modification of the humps is suggested for optimum performance.

Experimental modal analysis was conducted on a FR-4 epoxy fiber glass electronic printed circuit board (PCB) and a same size PCB with surface mount component to determine the modal parameters of the first four flexural vibration modes. Structural dynamic modification (SDM) and finite element analysis (FEA) techniques were utilized to predict the dynamic behavior of the boards when surface mount assemblies were attached. Details of modal testing procedures and analytical modeling involved in SDM and FEA were described. Processes of investigating suitable predicting model were presented. Results from the study indicate that the component can be modeled as a point mass under certain circumstance. But it is important to include the rotary inertia effects of the component in response prediction for the modes involving torsional vibration.

Simulations of bending and twisting of surface mounted assemblies have been performed using the hybrid analytical/experimental analysis approaches, and the results are presented. Analytical analyses were combined with experimental load-deformation characteristics of the surface mounted assemblies to predict the maximum allowable loadings and deflections that surface mounted assemblies can withstand before incurring failures. Simulation results obtained were in close agreement with the real loading situations.

A qualitative examination into the behavior of a variety of flexure joints was performed. It was found that of the initial seven joints examined only three had the characteristics to emulate the standard rotational pin joint. A complete evaluation of the three viable joint candidates was performed with the use of finite element modelling. The evaluation first focused on the joint itself, then the investigation turned to the performance of the joint in a simple mechanism, the four-bar linkage. The results indicate a dependence on geometry and loading for all the joint models studied.

The goal in developing submarines for military purposes is to make them high performance and highly maneuverable. Thus, the size of the submarine should be compatible with these goals. The size of the submarine is heavily dependent on the efficiency of the power plant. A nuclear power plant has many more advantages than a conventional diesel-electric powerplant. However, today's technology is not advanced enough to make a nuclear power plant small and light enough for a small submarine craft. Therefore, this thesis focuses on the fuel cell power plant study, configuration design, and dynamic behavior simulation. A mathematical model for the dynamic motion simulation is developed. The dynamic behavior simulations are carried out and analyzed.

A "hybrid" telerobotic simulation system that is suitable for telemanipulation rehearsal, operator training, human factors study and operator performance evaluation has been developed. The simulator also has the capabilities for eventual upgrade for supervisory control. It is capable of operation in the conventional rate-control, master/slave control and a data driven preprogrammed mode of operation. It has teach/playback capability which allows an operator to generate joint commands for real time teleoperation. For high-level task execution, the operator selects a specific task from a set of menu options and the simulator automatically generates the required joint commands. The simulator was developed using a three dimensional graphic model of an increasingly popular manipulator, TITAN 7F. A closed-form solution for inverse kinematics of the manipulator was found. Degeneracies from inverse kinematics solutions were observed to exist for certain arm configurations, although the manipulator can physically attain such configurations. An approach based on known facts about the manipulator geometry and physical constraints coupled with heuristics was used to generate physically attainable joint solutions from the inverse kinematics. The conditions that cause solution degeneracy were demonstrated to be related to singularity conditions. A novel object interaction detection strategy was implemented for more realistic telemanipulation. The object detection technique was developed based on the use of superellipsoid, which has a convenient inside-outside function for interference testing. The manipulator, with its end-effector and payloads, if any, were modeled as superquadric ellipsoids. A systematic way of determining transformation matrices between the superquadric manipulator links was developed. The interaction detection technique treats both moving and stationary objects in a consistent manner and has proved to be easy to implement and optimize for real-time applications. The feature has been applied for the simulation of pick-and-place operations and collision detection. It is also used to provide visual feedback as a low-cost force reflection and can be interfaced with a bilateral controller for force reflection simulation.