<p>In recent years Hardware-in-the-Loop HiL, has gained more and more</p><p>popularity within the vehicle industry. This is a more cost effective research alternative, as opposed to the tests done the traditional way, since in HiL testing the idea is to test the hardware of interest, such as an electronic control unit, in a simulated (or partially simulated) environment which closely resembles the real-world environment.</p><p>This thesis is ordered by Daimler Chrysler AG and the objective of this thesis is the developing of a cylinder-by-cylinder model for the purpose of emulation of misfire in a four-stroke SI-engine. This purpose does not demand a precise modelling of the cylinder pressure but rather an adequate modelling of position and amplitude of the torque produced by each cylinder. The model should be preferebly computaionally tractable so it can be run on-line. Therefore, simplifications are made such as assuming the rule of a homogenous mixture, pressure and temperature inside the cylinder at all steps, so the pressure model can be analytical and able to cope with the real-time demand of the HiL. The model is implemented in Simulink and simulated with different sample rates and an improvement is to be seen as the sample rate is decreased.</p>

The recent discovery that a spin-polarized current can exert a large torque on a ferromagnet, through direct transfer of spin angular momentum, offers the possibility of electrical current controlled manipulation of magnetic moment in nanoscale magnetic device structures. This so-called spin torque effect holds great promise for two applications, namely, spin torque oscillators (STOs) for wireless communication and radar communication, and spin transfer torque RAM (STT-RAM) for data/information storage.   The STO is a nanosized spintronic device capable of microwave generation at frequencies in the 1-65 GHz range with high quality factors. Although the STO is very promising for future telecommunication, two major shortcomings have to be addressed before it can truly find practical use as a radio-frequency device. Firstly, its very limited output power has to be significantly improved. One possibility is the synchronization of two or more STOs to both increase the microwave power and further increase the signal quality. Synchronization of serially connected STOs has been suggested in this thesis. In this configuration, synchronization relies on phase locking between the STOs and their self-generated alternating current. While this locking mechanism is intrinsically quite weak, we find that the locking range of two serially connected spin-valve STOs can be enhanced by over two orders of magnitude by adjusting the circuit I-V phase to that of an intrinsic preferred phase shift between the STO and an alternating current. More recently, we have also studied the phase-locking of STOs based on magnetic tunnel junctions (MTJ-STO) to meet the power specifications of actual application where the rf output levels should be above 0 dBm (1 mW). In addition to the spin torque terms present in GMR spin valves, MTJs also exhibit a significant perpendicular spin torque component with a quite complex dependence on both material choices and applied junction bias. We find that the perpendicular torque component modifies the intrinsic preferred I-V phase shift in single MTJ-STOs in such a way that serially connected STOs synchronize much more readily without the need for additional circuitry to change the I-V phase.   Secondly, equal attention has been focused on removing the applied magnetic field for STO operation, which requires bulky components and will limit the miniaturization of STO-based devices. Various attempts have been made to realize STOs operating in zero magnetic field. By using a tilted (oblique angle) polarizer (fixed layer) instead of an in-plane polarizer (standard STO), we show zero field operation over a very wide polarizer angle range without sacrificing output signal. In addition, the polarizer angle introduces an entirely new degree of freedom to any spin torque device and opens up for a wide range of additional phenomena.   The STT-RAM has advantages over other types of memories including conventional MRAM in terms of power consumption, speed, and scalability. We use a set of simulation tools to carry out a systematic study on the subject of micromagnetic switching processes of a device for STT-RAM application. We find that the non-zero k spin wave modes play an important role in the experimentally measured switching phase boundary. These may result in telegraph transitions among different spin-wave states, and be related to the back-hopping phenomena where the switching probability will decrease with increasing bias in tunnel junctions. / QC 20100819

Increasing demands for lower carbon dioxide emissions and fuel consumption drive technological developments for car manufacturers. One trend that has shown success for reducing fuel consumption in spark ignited engines is downsizing, where the engine size is reduced to save fuel and a turbocharger is added to maintain the power output. A drawback of this concept is the slower torque response of a turbocharged engine. Recent hardware improvements have facilitated the use of variable geometry turbochargers (VGT) for spark ignited engines, which can improve the transient torque response. This thesis addresses the transient torque response through three papers. Paper 1 presents the optimal control of the valve timing and VGT for a fast torque response. Optimal open-loop control signals are found by maximizing the torque integral for a 1-d simulation model. From the optimization it is found that keeping the ratio between exhaust and intake pressure at a constant level gives a fast torque response. This can be achieved by feedback control using vgt actuation. The optimal valve timing differs very little from a fuel consumption optimal control that uses large overlap. Evaluation on an engine test bench shows improved torque response over the whole low engine speed range. In Paper 2, model based, nonlinear feedback controllers for the exhaust pressure are presented. First, the dynamic relation between requested VGT position and exhaust pressure is modeled. This model contains an estimation of the on-engine turbine flow map. Using this model, a controller based on inverting the input-output relation is designed. Simulations and measurements on the engine show that the controller handles the strong nonlinear characteristic of the system, maintaining both stability and performance over the engine’s operating range. Paper 3 considers the dependence of the valve timing for the cylinder gas exchange process and presents a torque model. A data-based modeling approach is used to find regressors, based on valve timing and pressures, that can describe the volumetric efficiency for several engine speeds. Utilizing both 1-d simulations and measurements, a model describing scavenging is found. These two models combine to give an accurate estimation of the in-cylinder lambda, which is shown to improve the torque estimation. The models are validated on torque transients, showing good agreement with the measurements. / <p>QC 20120928</p>

The Brushless Doubly-Fed Machine (BDFM) has recently become an important research topic in the field of variable-speed AC drives. In recent studies, the BDFM has shown significant potential for improving the reliability and performance of AC drive systems, as well as reducing total system cost. While the BDFM offers several advantages over existing AC drives in steady-state operation, it suffers from dynamic instabilities and slow response times, and a feedback control system is necessary. The mathematics of the BDFM are much more complicated than those of a singly-fed machine, and thus traditional control methods can't be applied. In this thesis, a control method known as "Direct Torque Control" has been adapted from that of a singly-fed induction machine and successfully applied to the BDFM. The thesis begins by discussing the background of the BDFM, its open-loop operating characteristics, and some of the control considerations. The reduced-order system differential equations are introduced, and it is noted that they are coupled and nonlinear. Furthermore, all state variables are time-varying (but periodic), even in steady-state operation. In the controller development, it is found that a linear relationship exists between the desired torque/flux-level change and the d-q voltages to be applied to the control winding of the machine via the power-electronic converter. This linear relationship, together with a one-step-ahead predictor to compensate for computational delay, is successfully used to control the speed and efficiency of the machine, for a wide range of speeds and load torques. Numerous open- vs. closed-loop simulations are compared and summarized, and it is found that the performance of the BDFM is greatly improved in the closed-loop, with faster response and reduced oscillation. Further simulations investigating the robustness of the controller are summarized, and it is found that the controller is reasonably insensitive to errors in most of the the static machine parameters. Hardware implementation is briefly discussed but is not complete; laboratory results are not yet available but should be soon. Future controller considerations are then discussed; included among the recommendations are an on-line parameter estimator for use in adaptive control, and a controller for generator applications of the BDFM. / Graduation date: 1993

In recent years Hardware-in-the-Loop HiL, has gained more and more popularity within the vehicle industry. This is a more cost effective research alternative, as opposed to the tests done the traditional way, since in HiL testing the idea is to test the hardware of interest, such as an electronic control unit, in a simulated (or partially simulated) environment which closely resembles the real-world environment. This thesis is ordered by Daimler Chrysler AG and the objective of this thesis is the developing of a cylinder-by-cylinder model for the purpose of emulation of misfire in a four-stroke SI-engine. This purpose does not demand a precise modelling of the cylinder pressure but rather an adequate modelling of position and amplitude of the torque produced by each cylinder. The model should be preferebly computaionally tractable so it can be run on-line. Therefore, simplifications are made such as assuming the rule of a homogenous mixture, pressure and temperature inside the cylinder at all steps, so the pressure model can be analytical and able to cope with the real-time demand of the HiL. The model is implemented in Simulink and simulated with different sample rates and an improvement is to be seen as the sample rate is decreased.

Modern motion controllers of robot manipulators require knowledge of the system's dynamics in order to intelligently predict the torque command. The main objective for this thesis is to apply various motion controllers on a parallel direct drive robot in simulations and verify if one can take advantage of the model knowledge to improve performance of controllers. The controllers used in this thesis varied from simple PD control with position and velocity reference only applied independently at each joint to more advanced PD control with full dynamic feedforward term and computed torque control, which incorporate full dynamic knowledge of the manipulator. In the first part, a thorough study of deriving dynamic equation using Lagrange formulation has been presented as well as the actual derivation of dynamic equations for MINGUS2000. Next, in order to prepare proper sets of inputs for the simulations, detailed discussions of end effector trajectory path planning and inverse kinematics determination have been presented. Finally, background theories of various controllers used in this thesis have been presented and their simulation results on the closed-chain direct drive robot have been compared for verification purposes.

Finite Element Analysis on Planetary Three-Roll Rolling Advisor Prof.: Y. M. Hwang Student: F. H. Tsai ABSTRACT This paper used three-dimensional finite element code---Deform to analyze the plastic deformation behavior of material at the rolling-gap during planetary 3-roll rolling of rods or bars. The rigid-plastic model was used. The rolls are assumed to be rigid body and the change of temperature during rolling is ignored. The first part was used Deform to simulate the manufactured bars in factory. We analyzed the rolling force, torque and the shape after deformation. These results can offer knowledge for the design of actual rolling mill or pass schedule of the 3-roll rolling processes. The second part was compared with FEM and experiment. The simulation was made with the roll size and shape of a mini-type 3-roll rolling mill. We analyzed the rolling force, torque and the depth of spirals with different inclined angle, offset angle, roll shape and reduction.

Recently, many industries pursue the goal of automatic high-speed assembly and manufacturing. So how to meet the requirement of high-precision and high-speed automatic assembly equipment is an important issue. In automatic assembly equipment, the high-speed indexing devices have been widely used because of their features of high precision, no backlash, and compactness. With increasing operating speeds, the problems of shortage of motor power, poor indexing accuracy, vibration, and noise shall be solved. The torque compensation mechanism that is to be developed here is applied to keep motors operating at constant speeds by compensating the required torque. In previous researches, the researchers all devote to study torque compensation based on synchronous time chart. In this paper, it is aimed at compensation of the time control chart according the point of view of energy and the system model is built to simulate dynamic response of the system. Through the results of simulation and experiment, we will discover the relations between the compensation time chart and parameters about the high-speed indexing devices. It is expected to improve the precision of indexing devices according to those effective compensation time control charts.

Thesis (M.S.M.E.)--University of Delaware, 2009. / Principal faculty advisor: Xinyan Deng, Dept. of Mechanical Engineering. Includes bibliographical references.

A numerical panel method based on the potential flow theory has been refined and applied to the simulations of steady and unsteady cavitating flows inside water-jet pumps. The potential flow inside the water-jet is solved simultaneously in order to take the interaction of all geometries (blades, hub and casing) into account. The integral equation and boundary conditions for the water-jet problem are formulated and solved by distributing constant dipoles and sources on blades, hub and shroud surfaces, and constant dipoles in the trailing wake sheets behind the rotor (or stator) blades. The interaction between the rotor and stator is carried out based on an iterative procedure by considering the circumferentially averaged velocities induced on each one by the other. The present numerical scheme is coupled with a 2-D axisymmetric version of the Reynolds Averaged Navier-Stokes (RANS) solver to evaluate the pressure rise on the shroud and simulate viscous flow fields inside the pump. A tip gap model based on a 2-D orifice equation derived from Bernoulli’s obstruction theory is implemented in the present method to analyze the clearance effect between the blade tip and the shroud inner wall in a global sense. The reduction of the flow from losses in the orifice can be defined in terms of an empirically determined discharge coefficient (CQ) representing the relationship between the flow rate and the pressure difference across the gap because of the viscous effect in the tip gap region. The simulations of the rotor/stator interaction, the prediction of partial and super cavitation on the rotor blade and their effects on the hydrodynamic performance including the thrust/torque breakdown of a water-jet pump are presented. The predicted results, including the power coefficient (P*), head coefficient (H*), pump efficiency (η), thrust and torque coefficients (KT and KQ), as well as the cavity patterns are compared and validated against the experimental data from a series of on the ONR AxWJ-2 pump at NSWCCD. / text