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This paper describes an investigation into multi-core processing architecture for implementation of a Unified Chassis Control (UCC) algorithm. The multi-core architecture is suggested to reduce the operating load and maximization of the reliability to improve of the UCC system performance. For the purpose of this study, the proposed multi-core architecture supports distributed control with analytical and physical redundancy capabilities. In this paper, the UCC algorithm embedded in electronic control unit (ECU) is comprised of three parts; a supervisor, a main controller, and fault detection/ isolation/ tolerance control (FDI/FTC). An ECU is configured by three processors, and a control area network (CAN) is also implemented for hardware-in-the-loop (HILS) evaluation. Two types of multi-core architectures such as distributed processing, and triple voting are implemented to investigate the performance and reliability.

Electric vehicles are considered not only eco-friendly but also quieter than vehicles with conventional internal combustion engines. However, less noisy environments in cabins make passengers feel uncomfortable to moderate noise. This paper discusses noise reduction for electric vehicles radiated from traction motors. In the analysis of the noise generation mechanisms it is demonstrated that frequency ranges of the highest level in the noise spectrum of electromagnetic harmonic orders of the induction motor coincide with structural resonances of the motor housing. Interfacial friction between the inner and outer housings of the motor is employed in reducing structural vibration of the motor. Measured noise in the cabin and vibration at the motor housing indicates that slip damping presented from interfacial friction between the inner and outer housing is effective in reducing noise from the traction motor and in the cabin.

In this paper an effective technology of virtual thermal test of disc brake with several advanced analytic techniques was presented. With the virtual thermal test process, thermal performance of brake system could be easily evaluated without any possibility of great errors that used to happen in the past. In addition to the classical result of CFD, this virtual thermal test produced several valuable applications such as thermal deformation of rotor, optimization of thermal performance and estimation of braking distance.

This paper describes a lateral disturbance estimator for an application to a Motor Driven Power Steering (MDPS)-based driving assistant system. A vehicle motion can be disturbed laterally by wind force or load from bank angle acting on the vehicle in the lateral direction. An MDPS-based driving assistant system can be used to reduce steering effort of a human driver in a driving situation with lateral disturbance. In designing the MDPS-based driving assistant system, the lateral wind disturbance should be estimated to determine an assistant torque. An estimator for the vehicle lateral disturbance estimation has been developed. The proposed estimator consists of two parts: a tire self-aligning torque estimator and the lateral disturbance estimator. The lateral disturbance estimator has been designed on the basis of a 2-DOF bicycle model with available sensor signals from the MDPS module. A numerical simulation has been conducted in order to evaluate the proposed estimator.

Not only for the carmakers but also for the automotive parts suppliers, cost reduction and short development cycle are strongly required to survive in highly competitive market. The simulation models predicting acoustic performance of cockpit module at early design stage could be a part of time-saving and cost-effective solution for those demands. Via experimental, analytical, and virtual statistical energy analysis (SEA) approach, the simulation models of cockpit module predicting acoustic performance are developed and validated. Recently proposed virtual SEA using FE models from crash analysis are useful to reduce the ambiguity of SEA modeling which could make a big difference in the result. The SEA models simulate the transmission loss tests of a cockpit module attached with several kinds of acoustical treatments between two connected reverberation chambers.

There have been many kinds of simplifications and limitations in evaluating the thermal performance of disc brake when using the analytic technologies which were established before. But now new technology of virtual test with several advanced analytic techniques was developed to evaluate the thermal performance without any possibility of great errors that used to happen for the earlier time-consuming analyses. As a result, it was estimated that the new virtual test technology could afford to replace the physical dynamo test since the reliability of virtual test technology was reasonably verified with the existing data measured in dynamo test.

The integrated control system of Electronic Stability Control (ESC) and Motor-Driven Power Steering (MDPS) improves vehicle performance and extends functions via CAN network without any hardware modification. Although the ESC and MDPS integrated system does not improve vehicle behavior directly, it can inspire drivers to steer to the right direction by changing steering torque assistance characteristics. There are two different ways to control both ESC and MDPS systems: Top-down and Parallel control mode. First, the Top-down control mode, which is already widely used on the market, imposes ESC on the additional functions of ESC+MDPS integrated system. On the contrary, the Parallel control mode distributes the functions to ESC and MDPS, therefore each system does their own role and cooperates on special events. In this study, the parallel control mode controller is proposed and compared with the Top-down control mode.

In-vehicle driving tests for evaluating performance of vehicle control devices are often time-consuming, expensive, and not reproducible. Using hardware-in-the-loop simulation scheme, actual control devices can be easily tested in real time in a closed loop with a virtual vehicle. This advantage has made HILS systems popular as testbench lately in automotive industries. This paper describes a PC-based HILS system for ABS that has been developed in Matlab environment with real-time rapid prototyping tools. Also presented in this paper is a semi-empirical vehicle dynamic model that has been designed to account for kinematic and compliant characteristics of the suspension system from rig tests.

An Electrical Parking Brake (EPB) system is a device that operates to park the vehicle automatically with the push of a button instead of using conventional hand or foot levers which in some ways makes it the first by wire type of brake system. As such, it is being considered in some vehicle architectures as an automatic redundant backup for vacuum-less brake systems or autonomous cars. The EPB system is generally divided into cable puller and motor on caliper (MOC) types. Recently, the MOC type EPB is being more widely applied in the global market due to product competitiveness and cost effectiveness. The MOC type EPB is composed of the caliper body, torque member, pad assembly, nut assembly and actuator. Among them, the caliper body and torque member play a main role in the robustness of the EPB system and occupy more than 80% of the total weight.

It is widely believed or speculated that higher pad compressibility leads to reduced brake squeal and that caliper design can affect brake squeal. After encountering anecdotal contradictory cases, this investigation was undertaken to systematically generate basic data and clarify the beliefs or speculations. In order to adjust pad compressibility, it is common to modify pad molding temperatures, pressures and times, which in addition to changing the compressibility, changes friction coefficient and physical properties of the pad at the same time. In order to separate these two effects, NAO disc pads were prepared under the same molding conditions while using different thicknesses of the underlayer to achieve different compressibilities, thus changing the compressibility only without changing the friction coefficient and physical properties of the pad.

Nowadays, brake squeal noise is one of the most difficult problems and is a big issue in the automobile industry. Finite element analysis is a useful tool in predicting the noise occurrence of a conventional brake system during the design stage. This paper explains the technical procedure and method to resolve the squeal noise with commercial software programs. Friction coefficient under the operating conditions of the brake system was considered as a variable with respect to disc velocity and there was a dynamic behavior within the pad assembly during brake action. First of all, our Finite Element (FE) model was verified using the results of the parts and assembly's FRF measurements and an inertia noise dynamometer, followed by complex eingen value analysis to detect unstable frequencies. Subsequently, mode analysis was conducted for each part of the brake system through the MAC values.

The effects of pad properties and thermal coning of discs on high speed judder were investigated using dynamometer and vehicle tests. The friction materials of different thermal conductivities were manufactured and the discs were design-modified to control the thermal coning during braking under high speed conditions. Brake Torque Variation(BTV) was measured to evaluate the judder propensity in the dynamometer tests and the vibration on steering wheel and brake pedal was measured in the vehicle tests. The results showed that the increase of thermal conductivity of pad could not affect the judder propensity during high speed braking below 350°C of disc temperature, however better disc design reduced judder propensity due to the lower thermal deformation. Moreover, the increase of pad compressibility can reduce judder propensity due to the increase of damping capacity.

This paper proposes a simplified method to make the flux table considering the magnetic flux variation of the IPMSM (Interior Permanent Magnet Synchronous Machine) caused by temperature change in vehicle traction applications. Nowadays, normally an IPMSM with a rare-earth magnet is used for HEV traction applications. But because the flux density of the magnet varies with temperature, the optimal operating points, such as MTPA (Maximum Torque Per Ampere) and MTPV (Maximum Torque Per Voltage) of the motor drift according to temperature change. Those operating points can be expressed in a lookup table, that is, a flux table obtained by off-line experiment, which produces the DQ-axis current command with respect to the torque and flux reference. To reflect this temperature dependence in control, usually flux tables are generated at high, medium and low temperatures. Conventionally, all the three tables are constructed by experiment, which takes a great deal of time.

The history of the brake system for the passenger vehicles is no shorter than that of the automobile itself. With the long history, its performance, efficiency and reliability have been dramatically improved and as a result, even leading brake system suppliers now find it very difficult to come up with breakthrough ideas for further optimization of the current brake systems. In addition, as the powertrain of the vehicles has also been improved, the requirements of the brake system have become much more severe than before, leading to a trend of increasing the system size and weight especially for the parts belong to unsprung mass. In the case of high-end vehicles, the system was further optimized using expensive materials such as ceramic, carbon-fiber, etc. However, most normal vehicles have been developed without any significant changes in the existing systems. This decade-long trend of developing braking parts has seen a big change “electrification of the vehicle”.

The main role of CAB(side curtain airbag) is to protect the occupant's head in the event of side crash. The updated US NCAP for model year 2010 requires more extended coverage of CAB. It is not only required to cover the 50th%ile driver but also the 5th%ile driver and rear passenger. Although the general safety analysis model using only concerned sub-structure of the vehicle and prescribed structural motion is sufficient to handle frequent jobs, the analysis model with increased efficiency is needed when optimization is to be studied as it requires more runs and the model gets enlarged to consider extended sub-structure. In this study, three types of simplified analysis models are introduced. The first has an impactor which is composed of the head and neck with prescribed translational motions. It only uses the upper parts of the original sub-structure hence the run time is saved by 60∼70%.

Corrosion stiction at the contact interface between a brake friction material and a gray iron disc under the parking brake condition was investigated by evaluating the possible parameters that affect the shear force to detach the corroded interface. Using production brake friction materials, comprising non-steel and low-steel types, corrosion tests were carried out by pressing the brake pad onto the gray iron disc using a clamp at various conditions. Results showed that the shear force to detach the corroded interface tended to increase with applied pressure and corrosion time. On the other hand, porosity, acidity, and hydrophobicity of the friction material did not show a reliable correlation to the stiction force. The poor correlation of the stiction force with the friction material properties indicated that the stiction force was not determined by a single factor but governed by multiple parameters including surface contact areas and inhomogeneity of the ingredients.

Drivers continually require steering performance improvement, particularly in the area of feedback from the road. In this study, we develop a new electrically-assisted steering logic by 1) analyzing existing steering systems to determine key factors, 2) modeling an ideal steering system from which to obtain a desirable driver torque, 3) developing a rack force observer to faithfully represent road information and 4) building a feedback compensator to track the tuned torque. In general, the estimator uses the driver torque, assist torque and other steering system signals. However, the friction of the steering system is difficult to estimate accurately. At high speed, where steering feeling is very important, greater friction results in increased error. In order to solve this problem, we design two estimators generated from a vehicle model and a steering system model. The observer that uses two estimators can reflect various operating conditions by using the strengths of each method.

EMB (Electro-Mechanical Brake) which converts electrical motor power to brake clamping force at each wheel is a system that has been investigated and developed by various automotive part suppliers through the years. In particular, as the number of electrically powered vehicles, such as hybrid electric vehicles, electric vehicles and fuel cell electric vehicles, has expanded, the EMB has received increased interest due to its fast response that is much suited for effective cooperative control with regenerative braking. However, issues such as cost competitiveness, reliability and regulations need to be solved for commercialization [1-2]. A new concept, the hybrid Electro-Mechanical Brake (hEMB) is characterized by a dual piston structure linked by hydraulics inside of the caliper. It is possible to reduce the required motor power and increase the level of emergency back-up braking through the amplification effect of the dual piston mechanism [3].

Future technology trends of commercial vehicle steering components can be divided into three types. Environment-friendly technologies for environment-related regulations such as reducing emissions and improving fuel efficiency, and technology for driving convenience using electric steering control systems, and safety technology to protect drivers, passengers, nearby vehicles and pedestrians. Heavy duty commercial vehicles require a high-power steering system that used engine-driven hydraulic pump systems (generally used min 120bar, 17Liter/min) compared to passenger cars. In recent technical trend, In order to improve fuel efficiency and realize autonomous driving technology, we designed EHPS and Motor driven electric control actuator with the same structure as C-EPS.

Recently, there’s a massive flow of change in the automotive industry with the coming era of electric vehicles and self-driving (autonomous) vehicles. The automotive braking system field is not an exception for the change and there are not only lots of new systems being developed but also demands for researches for optimizations of conventional brake systems fitting to the newly appeared systems such as E-Booster and Electric Motor Brake (EMB) Caliper. Taking the Electric Motor Brake Caliper for example, it is considered as a very important and useful system for autonomous vehicles because the motor actuator of the caliper is much easier to control with ECUs compared to the conventional hydraulic pressure system. However, easy of control is not the only thing that excites brake system engineers.