Micro deformation of automobile hood in dipping process using stiffness

Technicians have been going through trial-and-error processes to solve very small or micro deformation on automobile hood during the painting process. In order to establish a systematic improvement procedure which can replace the time-consuming trial-and-error method to reduce defects, an accurate analysis of how micro deformation occurs during the painting process is needed. We have utilized a stiffness scanning method in automobile hood and reverse engineering to build up a reliable and accurate structural analysis and measurement procedures. We measured the load-stroke data at critical locations on automobile hood through stiffness scanning to determine material constants closest to the measurement by assuming several critical hood parts, such as sealer inside the hood, hemming part, spot weld part, and other uncertain joints, as virtual elastic materials. After setting the difference between analytical and measured load-stroke data as an objective function, we computed and minimized it by using the response surface method and partial differentiation of the object function. As a result, by obtaining the reliability was over 91%, which showed a strong correlation between analysis and measured results. By comparing the actual strain measured in real painting lines with calculated strain, we confirmed the validity of our structural analysis method. It was concluded that the proper analysis tool could be utilized in determination of optimal locations of supports during the painting process.     

Viable combined cycle design for automotive applications

A relatively new approach for improving fuel economy and automotive engine performance involves the use of automotive combined cycle generation technologies. The combined cycle generation, a process widely used in existing power plants, has become a viable option for automotive applications due to advances in materials science, nanotechnology, and MEMS (Mico-Electro Mechanical Systems) devices. The waste heat generated from automotive engine exhaust and coolant is a feasible heat source for a combined cycle generation system, which is basically a Rankine cycle in the context of this study. However, there are still numerous technical issues that need to be solved before the technology can be implemented in automobiles. A simulation was performed to examine the amount of waste energy that could be recovered through the use of a combined cycle system. A simulation model of the Rankine cycle was developed using Cycle-Tempo software. The simulation model was ultimately used to evaluate the rate of waste heat recovery and the consequential increase in the overall thermal efficiency of the engine with the combined cycle generation system under typical engine operating conditions. The most effective automotive combined cycle system recovered 68% of the waste heat from the exhaust and coolant, resulting in a 6% improvement in engine efficiency. The results are expected to be beneficial for evaluating the feasibility of combined cycle generation systems in automotive applications.     

Modeling and control of an anti-lock brake and steering system for cooperative control on split-mu surfaces

The brake and steering systems in vehicles are the most effective actuators that directly affect the vehicle dynamics. In general, the brake system affects the longitudinal dynamics and the steering system affects the lateral dynamics; however, their effects are coupled when the vehicle is braking on a non-homogenous surface, such as a split-mu road. The yaw moment compensation of the steering control on a split-mu road is one of the basic functions of integrated or coordinated chassis control systems and has been demonstrated by several chassis suppliers. However, the disturbance yaw moment is generally compensated for using the yaw rate feedback or using wheel brake pressure measurement. Access to the wheel brake pressure through physical sensors is not cost effective; therefore, we modeled the hydraulic brake system to avoid using physical sensors and to estimate the brake pressure. The steering angle controller was designed to mitigate the non-symmetric braking force effect and to stabilize the yaw rate dynamics of the vehicle. An H-infinity design synthesis was used to take the system model and the estimation errors into account, and the designed controller was evaluated using vehicle tests.     

Validation of the 6-dof vehicle dynamics model and its related VBA program under the constant radius turn manoeuvre

For a 6-dof (degrees of freedom) nonlinear vehicle dynamics model and its related VBA (Visual Basic for Applications) program, which were recently derived and coded by the authors, validations are carried out under the constant radius turn manoeuvre. This model has the uniqueness that the longitudinal translation, lateral translation and yaw rotation of a platform are described by an inertial ground coordinate system and the body-roll, body-pitch, and body-yaw rotations by a platform-fixed coordinate system. The simplified STI tire model is applied for the calculation of combined longitudinal and lateral tire forces. Vehicles used in the calculation are a NISSAN DATSUN 210 (manufactured in 1980) and a HONDA ACCORD (1984). The calculation results of the present 6-dof model are compared with the published test data and those of a simpler 3-dof lateral dynamic equation based on another coordinate system. As a result of the comparison, the present 6-dof results agree very well with those of the 3-dof model and give a partial consistency with the test data.     

Analysis of a large injection-molded body using knowledge-based flow process technology

A knowledge-based flow process is presented for large injection-molded body technology (LIMBT). Injection molding of a large body is a difficult technique because of the many factors and their interactions during the molding process. The proposed flow process can support LIMBT through integration of CAE(Computer-Aided Engineering), CAI (Computer-Aided Inspection), and monitoring systems. CAE and DOE (Design of Experiment) are used to construct an optimal mold design in terms of gates and runners and to identify working conditions for the molding process. CAI and monitoring systems with temperature sensors and pressure sensors can be used to inspect the physical molding process and the molded parts. The flow process of a large body is systematically planned and constructed using a knowledge-based flow process with DOE and computer-aided technologies. The proposed flow process is implemented for the molding process of an automobile front bumper fascia.     

Lateral controller design for an unmanned vehicle via Kalman filtering

This paper proposes a lateral control system for an unmanned vehicle that is designed to improve the responsiveness of the system with the use of a PD control. The vehicle heading error can be stabilized, and the transient response characteristics can be improved using the proposed controller. A mathematical model of the vehicle dynamics using two degrees of freedom was developed for the controller design. The waypoint tracking method for autonomous navigation was tested with incorporation of the Point-to-Point algorithm with position and heading measurements received from GPS receivers via Kalman filtering. The performance of the designed controller was verified through experiments with a real vehicle.     

Evaluation of the adequacy of neck injury indicators on bioridii in a lower-rear impact sled test

The BioRIDII (Biofidelic Rear-Impact Dummy II) is regarded as possessing similar characteristics to human volunteers and PMHS (post-mortem human subjects) in terms of its response to low-speed rear-impact tests. The biofidelity of the RID 2 (Rear-Impact Dummy 2) does not yield satisfactory results in comparison to the BioRIDII. Although a great deal of research on the repeatability and reproducibility of the BioRIDII has been conducted, the research results to date do not directly suggest the neck injury criteria and limit values that should be set in safety regulations. The purpose of this research is to evaluate neck injury indicators for the BioRIDII using low-speed rear-impact sled tests on three sets of BioRIDII ver-g. A series of sled tests was conducted to assess the adequacy of neck injury indicators in terms of the repeatability and reproducibility of the results obtained for the three BioRIDII dummies tested. The sled tests were performed according to the test procedure proposed by K-NCAP (the Korea New Car Assessment Program). Several neck injury indicators, namely, NIC, Nkm, upper- and lower-neck Fx, upper- and lower-neck Fz and My, T1 X acc and Head X acc, were analyzed for each dummy. The results show that for some criteria, such as the lower-neck shear force and moment and T1 acceleration, the BioRIDII could be considered adequate.     

Stability Analysis of the Human Controlled Vehicle Moving Along a Curved Path

A method to study handling characteristics of a vehicle moving along a curved path is presented. A simple bicycle model and a feedback controller with proportional gain are used to simulate the vehicle and the driver. The lateral stability of the vehicle/driver system is analyzed by using the root locus method and numerical integration in the time domain. The effect of the curvature on the system stability is discussed in detail. A new suggestion is made for the look ahead distance to calculate the preview lateral error of the vehicle with respect to the center of the road. Interesting results are shown for some important parameters such as the gain factor, the vehicle speed and the curvature of the path. Possible extensions of the method to more general cases and other applications are discussed.     

Stereovision-based real-time occupant classification system for advanced airbag systems

Occupant classification in a passenger seat is one of the critical components for any advanced airbag system. Many automotive electronic suppliers and engineers predict that the camera will be the next generation sensor for active and passive safety systems because it has several advantages compared to other sensors. The present paper describes a stereovision-based occupant classification system (OCS) and intelligent algorithm with embedded system by which triggering of the airbag deployment can be controlled. The system consists of a pair of stereo cameras and dual Digital Signal Processor (DSP): the first DSP is for the stereo matching processing, and the second is for occupant classification. The results show that the reaches 97%, and the processing time is 960 ms. Such performance indicates that the feasibility of the system as an embedded OCS is high.     

Sequential Approximate Optimization of MacPherson Strut Suspension for Minimizing Side Load by Using Progressive Meta-Model Method

In a MacPherson strut suspension, the side load is inevitably generated and it causes friction at the damper reducing riding comfort. In this paper, to solve this problem, progressive meta-model based sequential approximate optimization (SAO) is performed to minimize the side load. To calculate the side load, a wheel travel analysis is performed by using flexible multi-body dynamics (FMBD) model of suspension, which can consider both finite element method (FEM) and multi-body dynamics (MBD). In the optimal design process, meta-model is generated by using extracted sampling points and radial basis function (RBF) method. As a result of optimal design, spring setting positions that minimize the side load are obtained and by using optimal spring setting positions, the suspension FMBD model was constructed.