Heungseob Kim

A study on an anti-lock braking system controller and rear-wheel controller to enhance vehicle lateral stability

Abstract This paper presents a mathematical vehicle model that is designed to analyse and improve the dynamic performance of a vehicle. A wheel slip controller for anti-lock braking system (ABS) brakes is formulated using a sliding mode controller and a proportional-integral-derivative (PID) controller for rear wheel steering is also designed to enhance the stability, steerability, and driveability of the vehicle during transient manoeuvres. The braking and steering performances of controllers are evaluated for various driving conditions, such as straight and J-turn manoeuvres. The simulation results show that the proposed full car model is sufficient to predict vehicle responses accurately. The developed ABS reduces the stopping distance and increases the longitudinal and lateral stability of both two-and four-wheel steering vehicles. The results also demonstrate that the use of a rear wheel controller as a yaw motion controller can increase its lateral stability and reduce the slip angle at high speeds.

Application of a sliding mode control to anti-lock brake system

This paper presents application method of a sliding mode wheel slip controller for ABS that improves the vehicle response and increases the safety on slippery road. Sliding mode wheel slip controller receives wheel slip ratio, vehicle velocity, longitudinal acceleration, and tire forces from vehicle model to generate braking pressures. In general, two solenoid valves, so called normal open and normal close valves, have been used to generate the hydraulic pressure necessary to generate proper braking force. In this paper, the valve operating method is proposed to implement the sliding mode control output in hydraulic unit of the ABS. The control performance is verified by using a HILS System that has a vehicle braking system controlled with On/Off solenoid valves.

DEVELOPMENT OF AN ACTIVE MUFFLER SYSTEM FOR REDUCING EXHAUST NOISE AND FLOW RESTRICTION IN A HEAVY VEHICLE

This paper presents an application of an active muffler system for reducing exhaust noise in heavy vehicles. The signal-to-noise ratio associated with the process of estimating the transfer function of a secondary path was improved using conventional inverse modeling combined with an adaptive line enhancer as a control strategy. The simplified passive muffler using 2-duct perforated elements was combined with the active muffler system instead of a conventional passive exhaust system to reduce exhaust noise and flow restriction simultaneously. In experiments to estimate the transfer function of a secondary path, estimates using the inverse modeling method alone show many errors at the dominant frequencies of primary noise. Results obtained using the proposed algorithm correspond well to the actual transfer function as estimated without the primary noise. Control experiments with the proposed active muffler system have been implemented for stationary and driving states, respectively. Compared to the conventional passive muffler, the experimental results showed that the proposed active muffler could reduce the backpressure up to 60% as well as the overall sound pressure level below about 2200 rpm.

Demonstration of non-collocated vibration control of a flexible manipulator using electrical dynamic absorbers

This paper describes an experimental study into the vibration control of a servo system comprising a servo motor and a flexible manipulator. Two modes of the system are controlled by using the servo motor and an accelerometer attached to the tip of the flexible manipulator. The control system is thus non-collocated. It consists of two electrical dynamic absorbers, each of which consists of a modal filter and, in case of an out-of-phase mode, a phase inverter. The experimental results show that each absorber acts as a mechanical dynamic vibration absorber attached to each mode and significantly reduces the settling time for the system response to a step input.

The Study on the Influence of Pad Wear on Brake Squeal Analysis

This paper studies the effect of pad at initial stage and wear during braking on the dynamic contact pressure distribution. Wear is influenced by variable factor (contact pressure, sliding speed, radius, temperature) during dynamic braking and variation in contact pressure distribution. Many researchers have conducted complex eigenvalue analysis considering wear characteristic with Lim and Ashby wear map. The conventional analysis method is assumed the pad has smooth and flat surfaces. The purpose of this paper is to validate that wear rate induced by braking is considered for the precise squeal prediction. After obtaining pad wear from experiment, it is incorporated with FE model of brake system. Finally, the comparisons in fugitive nature of squeal will be carried out between the complex eigenvalue analysis and noise dynamometer experiment.

Analysis of the Front Disk Brake Squeal Using Kriging Method

Disc brake noise is an important customer satisfaction and warranty issue for many manufacturers as indicated by technical literature regarding the subject coming from Motor Company. This research describes results of a study to assess disk brake squeal propensity using finite element methods and optimal technique (Kriging). In this study, finite element analysis has been performed to determine likely modes of brake squeal. This paper deals with friction-induced vibration of disc brake system under contact friction coefficient. A linear, finite element model to represent the floating caliper disc brake system is proposed. The complex eigen-values are used to investigate the dynamic stability and in order to verify simulations which are based on the FEM model. In this paper, Kriging from among the meta-modeling techniques is proposed for an optimal design scheme to reduce the brake squeal noise.

A study on real time integrated lane detection and vehicle tracking method with side-mirror cameras

Vehicle detection in real-time from rear-side of a host vehicle is one of important problems in Lane Change Assistance. In this paper, we propose a vision system for real-time vehicle and lane detection and tracking using two cameras, which are equipped under the wing mirror both left and right side. From the input images, EDLines algorithm is used for line segment detection in real-time. According to the achieved data, lane detection is developed by analyzing angles of the line segments, and area between two lanes on the same side of vehicle is defined. In the vehicle detection, based on the brightness and darkness between vehicle and road, vehicle is detected in real-time using the simple algorithm. Finally, kalman filter is used in vehicle tracking for vehicle information such as distance or speed.

A Method for Rear-side Vehicle Detection and Tracking with Vision System

This paper contributes to development of a new method for detecting rear -side vehicle s and estimat ing the position s for blind spot region or providing the lane change information by using vision systems . Because the real image acquired during car driving has a lot of information including the target vehicle and background image as well as the noises such as lighting and shading, it is hard to extract only the target vehicle agains t the background image with satisfied robustness. In this paper, the target vehicle has been detected by repetitive image processing such as sobel and morphological operations and a Kalman filter has been also designed to cancel the background image and pr event the misreading of the target image. The proposed method can get faster image processing and more robustness rather than the previous researches. Various experiments were performed on the highway driving situations to evaluate the performance of the p roposed algorithm.

Comparison of model reference and map based control method for vehicle stability enhancement

A map based controller method to improve a vehicle lateral stability is proposed in this study and compared with the conventional method, a model referenced controller. A model referenced controller to determine compensated yaw moment uses the sliding mode method, but the proposed map based controller uses compensated yaw moment map acquired by vehicle stability analysis. Vehicle stability region is calculated by topological method based on trajectory reversal method. A two degree-of-freedom vehicle model and Pacejkas tire model used to evaluate the proposed map based controller. The control performance of two methods are compared under various road conditions and driving inputs. Model referenced control method needs control input to satisfies linear reference model, and then generates unnecessary tire lateral forces, it may lead to worse performance than uncontrolled vehicle with step steer input in low friction road. As the results of simulation, map based controller seems to be better than model referenced in the viewpoint of stability.

A method of determining flow stress and friction factor using an inverse analaysis in ring compression test

An inverse analysis been applied to obtain the flow stress of the material. In this method, a ring-shaped specimen is compressed between two flat tools. This procedure employs, as the object function of inverse analysis, the balance of measured loads and reaction forces calculated by using rigid-plastic finite element method. The balance is explicit scalar function of flow stress which is a function of some unknown constants. For minimizing the balance, Newton-Raphon scheme is used. The friction factor, m, between flat tools and the specimen is determined by using friction area-divided method. The proposed method allows an accurate identification by avoiding the usual assumptions made in order to convert experimental measures into stress-strain relation. In this paper, the proposed method is numerically tested. A commercial pure aluminum was selected, as an example, to apply the method and the results are compared with stress-strain relation obtained by experiments.