• Journal of Mechanical Science and Technology
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• 제15권5호
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• pp.569-579
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• 2001

This study investigates the effects of operating conditions on the chattering of an automotive disk brake by experimental and computational methods. Design factors, which cause chattering in automobiles, have attracted great attentions for long time; but they are not well understood yet. For this study, we construct a brake dynamometer for measuring the disk surface temperature during chattering, and propose an efficient hybrid algorithm (combining FFT-FEA and traditional FEA program) for analyzing the thermo-elastic behavior of three-dimensional brake system. We successfully measure the judder in a brake system via the dynamometer and efficiently simulate the contact pressure variation by the hybrid algorithm. The three-dimensional simulation of thermo-mechanical interactions on the automotive brake, showing the transient thermo-elastic instability phenomenon, is presented for the first time in this academic community. We also find from the experimental study that the disk bulk temperature strongly influences the brake chattering in the automotive disk brakes.

• 제어로봇시스템학회논문지
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• 제18권6호
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• pp.519-525
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• 2012

Electric brake booster systems replace conventional pneumatic brake boosters with electric motors and rotary-todisplacement mechanisms including ECU (Electronic Control Unit). Electric booster brake systems require precise target pressure tracking and control robustness because vehicle brake systems operate properly given the large range of loading and temperature, actuator saturation, load-dependent friction. Also for the implement of imbedded control system, the controller should be selected considering the limited memory size and the cycle time problem of real brake ECU. In this study, based on these requirements, a sliding mode controller has been chosen and applied considering both model uncertainty and external disturbance. A mathematical model for the electric booster is derived and simulated. The developed sliding mode controller considering chattering problem has been compared with a conventional cascade PID controller. The effectiveness of the controller is demonstrated in some braking cases.

• Journal of Mechanical Science and Technology
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• 제15권10호
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• pp.1398-1407
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• 2001

In this paper an anti-lock brake system (ABS) for commercial buses is proposed based on a fuzzy-logic controller and a sliding-mode observer of the vehicle speed. The brake controller generates pulse width modulated (PWM) control inputs to the solenoid valve of each brake, as a function of the estimated wheel slip ratio. PWM control inputs at the brakes significantly reduce chattering in the brake system compared with conventional on-off control inputs. The sliding-mode observer estimates the vehicle speed with measurements of wheel speed, which is then sed to compute the wheel slip ratio. The effectiveness of the proposed control algorithm is validated by a series of computer simulations of bus driving, where the 14-DOF bus model is used.

• International Journal of Automotive Technology
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• 제7권6호
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• pp.697-702
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• 2006

The change in the critical speed due to surface temperature of automotive disk brakes may be analyzed both theoretically as well as experimentally. Juddering of disk brakes is closely related to its critical speed. In analyzing the critical speed, if $\sigma$ is positive, Disk develops TEI(Thermo-Elastic Instability) resulting in juddering in disk brakes. And $\sigma$ is affected not only by the critical speed but also by the initial temperature of disk surface. As the initial temperature of the disk surface rises, the critical speed decreases and juddering is developed more easily. Also, when hot spots are developed by TEI, they show large temperature difference in small local range.

• International Journal of Automotive Technology
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• 제5권2호
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• pp.123-133
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• 2004

This paper describes a robust and fast wheel slip tracking control using a moving sliding surface technique. A traction control system (TCS) is the active safety system used to prevent the wheel slipping and thus improve acceleration performance, stability and steerability on slippery roads through the engine torque and/or brake torque control. This paper presents a wheel slip control for TCS through the engine torque control. The proposed controller can track a reference input wheel slip in a predetermined time. The design strategy investigated is based on a moving sliding surface that only contains the error between the reference input wheel slip and the actual wheel slip. The used moving sliding mode was originally designed to ensure that the states remain on a sliding surface, thereby achieving robustness and eliminating chattering. The improved robustness in driving is important due to changes, such as from dry road to wet road or vice versa which always happen in working conditions. Simulations are performed to demonstrate the effectiveness of the proposed moving sliding mode controller.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.110-110
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• 2000

In this paper, an antilock brake system (ABS) for commercial vehicles is studied by considering the design of a fuzzy Logic controller with pulse width modulation (PWM). PWM method is used for generating solenoid valve inputs in order to cope with the chattering problem caused by the conventional on/off control The sliding mode observer is designed to estimate the vehicle longitudinal velocity and it is used to calculate the wheel slip ratio. The effectiveness of the proposed control algorithm was validated by simulations performed with a nonlinear 14-DOF vehicle model including the dynamics of the brakes.