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M.Ing. (Mechanical Engineering) / A hydromechanical traction system for a wheeled vehicle is being examined in order to generate information that will be applicable to the design of the drive system controller. The functional analysis of the drive system leads to the description of the system and component properties. A design methodology is proposed by which the system components could be dimensioned and the system layout constructed by taking into account the specified functional requirements concerning the system performance. An explicit description of power flow and manipulation of power flow in the drive system is given. The mechanisms by which the hydraulic machines are adjusted to manipulate power flow, are examined in detail so that their contribution to the dynamic behaviour of the total drive system can be described. , Experimental measurements are used to obtain a reliable description of the dynamic response of the adjustment mechanisms. An analytical model of the dynamic behaviour of the drive system is presented in block diagram format. The inherent multiple-input-multiple-output characteristic of the drive system with secondary controlled hydraulic motors is discussed. The block diagram is simplified to create linearized transfer functions that will depict the input-output-relationships. The effect of an accumulator on the dynamic response of the system is also given. Digital simulation programmes are constructed from the analytical model. The requirements of a vehicle traction system are interpreted and used as guidelines to conduct a functional design of the control system layout. The delivery of torque and the restriction of wheel spin for each of the wheel drive units, which is realised by secondary controlled hydraulic motors, are described in detail. A hypothetical drive system is considered and quantitive control system design information is generated, using the simulation programmes. Some aspects of the dynamic response of the system are discussed and it is shown that the adjustment mechanism has a big influence on the overall dynamic response of the system.

An electric motor drive is a power-electronic based system that is used to precisely control the position, speed or torque developed by motor. With the growing complexity of drive systems and the expansion of the use of fast acting power-electronic controllers, computer simulation models are used instead of an explicit mathematical description of a complex system. The aim of this research is to study the use of the simulation based design method for advanced motor drives. The major problem for simulation of a drive system performance is the presence of both fast and slow dynamics in its response that result in relatively long time simulations with a small time step. Moreover, the simulation-based optimal design has a repetitive nature. Therefore, the simulation-based optimal design of a drive system is massively time consuming and requires extensive computing resources. In this research reduced intensity computer models are used to overcome this problem.

An electric motor drive is a power-electronic based system that is used to precisely control the position, speed or torque developed by motor. With the growing complexity of drive systems and the expansion of the use of fast acting power-electronic controllers, computer simulation models are used instead of an explicit mathematical description of a complex system. The aim of this research is to study the use of the simulation based design method for advanced motor drives. The major problem for simulation of a drive system performance is the presence of both fast and slow dynamics in its response that result in relatively long time simulations with a small time step. Moreover, the simulation-based optimal design has a repetitive nature. Therefore, the simulation-based optimal design of a drive system is massively time consuming and requires extensive computing resources. In this research reduced intensity computer models are used to overcome this problem.

Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 75-78).

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Belt drives are used in numerous applications to transmit power between various machine elements. One limitation of the use of belt drives is the poor convergence of complex models which did not make them applicable for manufacturing use in industry. A source of convergence failure is the sharp changes in the solution. It is believed that the inclusion of an Elastic/Perfectly-Plastic (EPP) friction law into the belt/pulley contact mechanics can yield mathematical models with enhanced accuracy. This new friction model more accurately captures the true behavior of an elastic belt that exhibits microslip prior to fully-developed slip than previous regularized friction models. The Elastic/Perfectly-Plastic friction model was applied to a two-pulley flat belt system, and the equations of motions were derived using Hamilton's Principle. The results from the analytical model were compared to results from a finite element model. It was found that, unlike Coulomb's Law, the solutions with the EPP model had no slope discontinuities in the normal force. The elimination of these slope discontinuities could potentially help alleviate convergence issues for more complex models. It was also found that if the EPP spring stiffness is too small, then the belt cannot undergo the prescribed tension change. If it is too large, then the EPP model approaches Coulomb's Law and sharp changes appear. The Elastic/Perfectly-Plastic friction model was also applied to a v-belt model. It was found that the solutions and convergence properties with the EPP friction model were similar to the solutions with the Coulomb friction model. When compared to Coulomb's Law, the range of possible high tensions for a given low tension was reduced slightly for the EPP friction. Convergence fails due to sharp changes of the inclination angle and the sliding angle. Because the sharp changes occur when the belt exits the pulley, the EPP friction model cannot smooth the slope discontinuities.

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No description available.