Capacity estimation of torque converters with piston holes using the response surface method and an artificial neural network

In new slim torque converters, lock-up clutches are used to provide high fuel efficiency at low speed. However, the slimness of the converters causes difficulty in heat dissipation, which may damage the friction material and shorten its life span. A cooling hole in the lock-up piston reduces the heat but also reduces the torque because oil flows through the hole due to the pressure difference between the two faces of the piston. In the early stages of the development of this type of torque converter, designers must consider the minimum flow rate required to cool the friction material and the minimum torque capacity required to transmit the engine torque. This research explored two methods of estimating these parameters. In the first method, an estimation equation was derived by combining the response surface method with physical properties such as the centrifugal force, a sudden expansion, a sudden contraction, and the steady flow energy equation. The second method involved the use of an artificial neural network. The feasibility of the estimates based on statistics and on the artificial neural network were confirmed in the design stage by comparing experimental and estimated data. An estimation program was created using the C#.Net language and has been used for actual torque converter designs by the Korea Powertrain Company.     

Measurement of roof deformation caused by vehicle rollover

A vehicle rollover is a critical accident that could have many causes. This paper describes a novel vision-based system for measuring vehicle roof deformation due to a rollover accident. A vision-based measurement system offers an overall view of structural deformation simply at low cost. Our measurement system was constructed using a Kinect camera from Microsoft, a battery, and a remote-controlled recording computer. Color images and distance maps can be obtained using two sensors embedded in the Kinect along with customized software, and the distance from the camera lens to a specific object can be calculated with a simple equation. To test our proposed approach, actual vehicle rollover experiments were conducted and the resulting roof deformations were compared to those indicated by our system. Moreover, cross-sectional image of Apillar was analyzed to calculate bending moment of inertia. From the research results, it was able to show that deformation errors were within 13 mm, and roof deformation was correlated with vehicle type, or vehicle curb weight.     

Experimental Study of Effects of Travel Time Distribution Information on Dynamic Route Choice Behavior

This study focuses on the possibility that providing travelers with information on travel time distribution, along with the existing travel time information, might affect their decision making and enhance traffic control. As an initial step to confirm the effectiveness of travel time distribution information, we use a laboratory experiment to obtain panel data of route choices when information is provided. The rationality of the behavior of the respondents and the characteristics of the route choice are first analyzed by aggregation analysis and then statistically examined by specifying a mixed logit route choice model. As a result, it is revealed that both travel time information and maximum travel time information significantly affect route choice behavior when a penalty is imposed for late arrival.     

Estimation of vehicle sideslip angle and tire-road friction coefficient based on magnetometer with GPS

This paper presents a method that estimates the vehicle sideslip angle and a tire-road friction coefficient by combining measurements of a magnetometer, a global positioning system (GPS), and an inertial measurement unit (IMU). The estimation algorithm is based on a cascade structure consisting of a sensor fusing framework based on Kalman filters. Several signal conditioning techniques are used to mitigate issues related to different signal characteristics, such as latency and disturbances. The estimated sideslip angle information and a brush tire model are fused in a Kalman filter framework to estimate the tire-road friction coefficient. The performance and practical feasibility of the proposed approach were evaluated through several tests.     

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.     

Hydro- and aerodynamic analysis for the design of a sailing yacht

The results of the design analysis for a sailing yacht’s hull and sails are reported. The results were used to confirm the design of a 30 ft long sloop, which was planned, designed, and built in Korea for the first time in history. Flows around a sailing yacht above and under the free surface were analyzed separately using both computational and experimental methods. For the underwater flow analysis, turbulent flow simulations with and without free surface wave effects were carried out for the canoe hull with keel/rudder. The computed drag and side forces on the hull model were compared with the measurement data obtained from the towing tank experiments. In order to assess the sail performance, another set of computations was carried out for the flow around a sail system composed of main and jib sails with a mast. The present study demonstrates that, for the design analysis of a sailing yacht, computational fluid dynamics techniques can be utilized with a reasonable level of confidence.     

Durability improvement of automotive V-belt pulley

Improving the durability of an automotive V-belt pulley, which is commonly used in an automotive powertrain to transfer power to other parts, is discussed. Fatigue life of the original V-belt pulley is predicted based on damage analysis by finite element analysis (FEA). Stress history of the pulley during operation was found by performing consecutive static analyses on the pulley as the pulley rotates. Assembly load (due to the tightening of the bolts) and operation load were considered to describe the actual load conditions in a durability test. The contact condition from the belt was calculated and applied to the surface of the pulley. Static analyses at 36 different positions of the pulley, every ten degrees of rotation, were performed to determine the stress history of the pulley during operation. Using stress history data calculated from FE analysis, damage over one rotation of the pulley was calculated and fatigue life, in number of rotations to failure, was estimated. An improvement to the durability of the pulley was investigated by modifying the design of the pulley using FE analysis results. Durability tests for the pulleys used in the analysis were carried out to verify the analytical results. Comparison between analysis and experimental results showed that analytical results correlated with the experimental results closely.     

Numerical study to evaluate the characteristics Of HVAC-related Parameters to reduce CO<Subscript>2</Subscript> concentrations in cars

Today, as people are spending increasing amounts of time in their cars, they have come to recognize that the car should function as a “residential” space. An eco-friendly indoor environment that provides comfort in terms of visual, tactile, and auditory senses is needed for the driver and the passengers. The quality of the car’s indoor environment was evaluated on various factors, such as indoor thermal comfort, indoor air quality, smell, and noise. For the indoor air quality, the typical pollutants that degrade the air quality are CO₂, volatile organic compounds, and exhaust gases. Especially, CO₂ has a direct relationship with drowsy driving which leads to traffic accidents. There have been many experimental and analytical studies to reduce the level of CO₂ in a short time, but analyses of parameters that affect indoor CO₂ concentration are insufficient and comprehensive standards for evaluating the car indoor CO₂ concentration do not yet exist. In this study, several parameters were selected that can influence the reduction rate of CO₂ concentration, and a series of computational analyses were conducted to study the results of these parameters in CO₂ reduction. Based on this study, a prediction equation for CO₂ concentration was derived. For this, a general full factorial design was used to evaluate the CO₂ reduction characteristic based on various parameters (ventilation mode, boarding condition, vent angle, mass flow rate, and operation mode), and then their effects were analyzed to obtain an evaluation database of indoor air quality. From that, a prediction equation was derived to estimate the indoor air quality, enabling us to evaluate the CO₂ concentration quickly that actually influences the human body without carrying out time-consuming CFD analyses for CO₂ concentration. This study will be useful in designing HVAC systems and establishing the control logic for effective improvement of the car’s indoor air quality in the future.