ARC Conference 2002

1B-2 Modeling and Control of an Alternative Steering System for Hybrid Vehicles Pradeep Setlur, Val Mills, Dr. John Wagner, and Dr. Darren Dawson Hybrid vehicles integrate an electric motor with accompanying battery pack and generator, an internal combustion engine, and potentially fuel cells to acquire greater fuel economy and reduced emission levels. Automotive subsystems such as hydraulic power steering cannot be consistently powered by a conventional hydraulic pump as the engine may be frequently turned-off to conserve energy. A need exists to investigate the dynamic behavior and control of these alternative steering systems. In this presentation, empirical and analytical mathematical models will be offered for a steer-by-wire rack and pinion steering unit. A continuous time-varying tracking controller will then be presented to ensure that the vehicle's position and orientation follow a reference vehicle trajectory. In this controller design, the tracking error is globally exponentially forced to a neighborhood about zero that can be made arbitrarily small (i.e., global uniformly ultimately boundedness). The controller also solves the set-point or "parking" problem as an extension of the tracking problem. Representative numerical results will be presented. 1B-3 Performance of a Continuously Variable Transmission in a Medium Duty Vehicle A Case Study Bernard Samuels, Pradeep Setlur, Nilabh Srivastava, Dr. John Wagner, Dr. Darren Dawson, and Dr. Imtiaz Haque The continuously variable transmission (CVT) offers a continuum of infinitely variable gear ratios between established minimum and maximum limits. This continuous gear ratio spectrum eliminates the unwanted jerks associated with manual and automatic transmissions while better accommodating the vehicle’s speed demands with the available engine power. Vehicles utilizing continuously variable transmissions offer improved engine efficiency over traditional vehicle powertrains. Although basic CVT designs have difficulty with high torque/low speed requirements, a power split continuously variable transmission (PSCVT) configuration offers both fixed gearing and adjustable pulleys to satisfy driving demands. Effective control of the variable radius pulleys allows the designation of engine torque/speed operating ranges to optimize overall system efficiency for the given operating condition. A multiple inertia power split continuously variable transmission model will be presented and integrated into the Vehicle Engine Simulation (VESIM) environment developed by the Automotive Research Center at the University of Michigan to facilitate the investigation of powertrain systems. Representative numerical results will be presented and discussed to demonstrate the performance of the PSCVT model for a class VI vehicle 1C Efficient NVH Analysis and Design Optimization of Vehicle Structures 1C-1 Energy Boundary Element and Hybrid Finite Element Developments N. Vlahopoulos and S.-B. Hong The Energy Boundary Element Analysis (EBEA) constitutes a new formulation for computing high frequency acoustic radiation. It has been utilized in one of the recent ARC case studies for evaluating the airborne noise in the vicinity of the vehicle and for making a comparison of the airborne acoustic field between a conventional and a hydraulic hybrid truck. The theoretical background and the validation of the EBEA will be presented. The EBEA constitutes a significant improvement over the traditional Statistical Energy Analysis (SEA) for high frequency exterior acoustic analysis. The SEA approximates an exterior domain as an assembly of several enclosed cavities and requires the definition of artificial damping and non-physical coupling loss factors between subsystems. The new EBEA formulation eliminates all these approximations. In addition, the hybrid FEA development effort is continued for coupling conventional FEA with EFEA. Analyses are performed using a conventional dense FEA model and a hybrid FEA approach for an assembly of plates spot-welded on a frame structure. Results between the two methods are compared successfully in the mid-frequency range. ARC Conference 2002: Symposia Program