Vehicle Design Highlights

ARCHIVES

Title: Suppression of heavy-truck driver-seat vibration using sliding-mode control and quantitative feedback theory

Author(s): N I Rajapakse, G S Happawana, Y Hurmuzlu

Source: Proceedings of the I MECH E Part I Journal of Systems and Control Engineering

Volume: 221 No 5: Page: 769 - 779. July 2007

DOI: 10.1243/09596518JSCE216

Publisher: Professional Engineering Publishing

Abstract: The current paper presents a robust control method that combines sliding-mode control (SMC) and quantitative feedback theory (QFT) for designing a driver seat of a heavy vehicle to reduce driver fatigue. A mathematical model is considered to analyse tracking control characteristics through computer simulation in order to demonstrate the effectiveness of the proposed control methodology. The SMC is used to track the trajectory of the desired motion behaviour of the seat. However, when the system enters into sliding regime, chattering occurs owing to switching delays as well as vehicle system vibrations. The chattering is eliminated with the introduction QFT inside the boundary layer to ensure smooth tracking. Furthermore, using SMC alone requires higher actuator forces for tracking than using both the control schemes together, and causes various problems in selecting hardware. Problems with noise amplification, resonances, presence of uncertainties, and unmodelled high-frequency dynamics can largely be avoided with the use of QFT over other optimization methods. The main contribution of the present paper is to provide guidance in designing the controller to reduce heavy vehicle seat vibration so that the driver's sensation of comfort maintains a certain level at all times.

Title: Integrated design of function, usability, and aesthetics for automobile interiors: state of the art, challenges, and solutions

Author(s): Y Lin, W J Zhang

Source: Proceedings of the I MECH E Part I Journal of Systems and Control Engineering

Volume: 220 Page: 697 - 708. November 2006

DOI: 10.1243/09596518JSCE231

Publisher: Professional Engineering Publishing

Abstract:
This paper presents a critical review of aesthetic design with a focus on the application of vehicle interiors. In particular, the following aspects of the subject are covered: first, aesthetics and its relevance to product design; second, the integrated aesthetic design process; third, the evaluation of aesthetic responses; fourth, the notion of intelligent vehicle interiors; fifth, the computational methods for aesthetic design. Shortcomings in existing studies related to vehicle aesthetic design are identified and analysed. The methodology employed to conduct this review is such that a set of questions important to these aspects are defined first, and then existing studies are analysed on the basis of their provision of answers to these questions. At the end, several ideas are proposed, which are brought together as a software environment, with the goals of overcoming these identified shortcomings and advancing the automobile interior aesthetic design technology.

Title: The relationship of seat backrest angle and neck injury in low-velocity rear impacts

Author(s): J Latchford, E C Chirwa, T Chen, M Mao

Source: Proceedings of the I MECH E Part D Journal of Automobile Engineering

Volume: 219 Page: 1293 - 1302. November 2005

DOI: 10.1243/095440705X34946

Publisher: Professional Engineering Publishing

Abstract:
Car-rear-impact-induced cervical spine injuries present a serious burden on society and, in response, seats offering enhanced protection have been introduced. Seats are evaluated for neck protection performance but only at one specific backrest angle, whereas in the real world this varies greatly owing to the variation in occupant physique. Changing the backrest angle modifies the seat geometry and thereby the nature of its interaction with the occupant.

Low-velocity rear-impact tests on a BioRID II anthropomorphic test dummy (ATD) have shown that changes in backrest angle have a significant proportionate effect on dummy kinematics. A close correlation was found between changes in backrest angle and the responses of neck injury predictors such as lower neck loading and lower neck shear but not for the neck injury criterion NICmax. Torso ramping was evident, however, with negligible effect in low-velocity impacts.

The backrest angle ranged from 20° to 30° whereas the BioRID II spine was adapted to a range from 20° to 26.5°. Nevertheless, in general, instrumentation outputs correlated well, indicating that this ATD could be used for evaluating seats over a 20-30° range rather than solely at 25° as required by current approval test specifications.

Title: Objective evaluation of the rumbling sound in passenger cars based on an artificial neural network

Author(s): Sang-Kwon Lee; Byung-Soo Kim; Dong-Chul Park

Source: Proceedings of the I MECH E Part D Journal of Automobile Engineering

Volume: 219 Page: 457 - 469. April 2005

DOI: 10.1243/095440705X11112

Publisher: Professional Engineering Publishing

Abstract: A rumbling sound is one of the most important sound qualities in a passenger car. In previous work, a method for objectively evaluating the rumbling sound was developed based on the principal rumble component. In the present paper, the rumbling sound was found to relate effectively not only to the principal rumble component but also to the loudness and roughness. The last two subjective parameters are sound metrics in psychoacoustics. The principal rumble component, roughness, and loudness were used as the sound metrics for the development of the rumbling index to evaluate the rumbling sound objectively. The relationship between the rumbling index and these sound metrics is identified by an artificial neural network. Interior sounds of 14 passenger cars were measured, and 21 passengers subjectively evaluated the rumbling sound qualities of these interior sounds. Through this research, it was found that the results of these evaluations and the output of a neural network have a high correlation. The rumbling index has been successfully applied to the objective evaluation of the rumbling sound quality of mass-produced passenger cars.

Title: The application of artificial neural networks to the characterization of interior noise booming in passenger cars

Author(s): S-K Lee; H-C Chae

Source: Proceedings of the I MECH E Part D Journal of Automobile Engineering

Volume: 218 Page: 33 - 42. October 2004

DOI: 10.1243/095440704322829146

Publisher: Professional Engineering Publishing

Abstract: The booming index has been developed recently to evaluate the sound characteristics of passenger cars. Previous work maintained that booming sound quality is related to loudness and sharpness - the sound metrics used in psychoacoustics - and that the booming index is developed by using the loudness and sharpness for a signal within whole frequencies between 20 Hz and 20 kHz. In the present paper, the booming sound quality was found to be effectively related to the loudness at frequencies below 200 Hz; thus the booming index is updated by using the loudness of the signal filtered by the low pass filter at frequencies under 200 Hz. The relationship between the booming index and the sound metric is identified by an artificial neural network (ANN). Interior sounds of 10 passenger cars were measured, and 21 persons subjectively evaluated the booming sound qualities for these interior sounds. Throughout this research, it was found that there is a high correlation between the results of these evaluations and the output of a neural network. The updated booming index has been successfully applied to the objective evaluation of the booming sound quality of mass-produced passenger cars.