Vehicle Design Highlights

ARCHIVES

Title: Vehicle yaw-inertia- and mass-independent adaptive steering control

Author(s): J Wang, M F Hsieh

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

Volume: 223, Number 9 / Sept 2009 Pages 1101-1108

DOI: 10.1243/09544070JAUTO1135

Publisher: Professional Engineering Publishing

Abstract:
This paper describes a vehicle stability control (VSC) system using a vehicle yaw-inertia- and mass-independent adaptive control law. As a primary vehicle active control system, VSC can significantly improve vehicle driving safety for passenger cars and enhance trajectory tracking accuracy for other applications such as autonomous, surveillance, and mobile robot vehicles. For the designs of vehicle dynamic control systems, vehicle yaw inertia and mass are two of the most important parameters. However, in practical applications, vehicle yaw inertia and mass often change with vehicle payload and load distribution. In this paper, an adaptive control law is proposed to treat the vehicle yaw inertia and mass as unknown parameters and automatically address their variations. For the proposed adaptive control law, asymptotic stability of the yaw rate tracking error was proved by a Lyapunov-like analysis for certain vehicle architectures under some reasonable assumptions. The performance of the yaw-inertia- and mass-independent adaptive VSC system was evaluated under several driving conditions (i.e. double lane changing on a slippery surface and braking on a split-μ surface tests) through simulation studies using a high-fidelity full-vehicle model provided by CarSim®.

Title: The mechanical hybrid vehicle: an investigation of a flywheel-based vehicular regenerative energy capture system

Author(s): U Diego-Ayala, P Martinez-Gonzalez, N McGlashan, K R Pullen

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

Volume: 222, Number 11 / Nov 2008 Pages 2087-2101

DOI: 10.1243/09544070JAUTO677

Publisher: Professional Engineering Publishing

Abstract:
Capturing braking energy by regeneration into an onboard energy storage unit offers the potential to reduce significantly the fuel consumption of vehicles. A common technique is to generate electricity in the motors of a hybrid electric vehicle when braking, and to use this to charge an onboard electrochemical battery. However, such batteries are costly, bulky, and generally not amenable to fast charging as this affects battery life and capacity. In order to overcome these problems, a mechanical energy storage system capable of accepting and delivering surges of power is proposed and investigated. A scale physical model of the system, based around a flywheel, a planetary gear set, and a brake, was built and operated in a laboratory. Tests showed that the proposed system could be used to store and provide braking energy between a flywheel and a vehicle, the latter emulated by an air-drag dynamometer. This validated the operating principle of the system and its computational model. Further, a computational analysis of a full-size vehicle incorporating the mechanical energy storage system was conducted. The results showed that the utilization of this system in a vehicle, when compared with a conventional vehicle, led to reductions in emissions and fuel consumption.

Title: Model-based development for an electric power steering system

Author(s): W Ren, H Chen, J Song

Source: Proceedings of the I MECH E Part C Journal of Mechanical Engineering Science

Volume: 222, Number 7 / July 2008 Pages 1265-1269

DOI: 10.1243/09544062JMES925

Publisher: Professional Engineering Publishing

Abstract: A model-based development method for electric power steering (EPS) system has been explored. A practicable model for the EPS system has been established in a full vehicle mechanical system environment. The performance of the electric control system of the EPS system has been evaluated in this static analysis environment. The model has then been used in a dynamic test environment based on dSPACE hardware and software, including Software-in-the-Loop and Hardware-in-the-Loop. The test result validates the simulation model, and shows that this development method can be used to evaluate the conceptual design of the EPS system as well as the control software design and testing.

Title: Finite element analysis of wear and its effect on squeal generation

Author(s): A.R.Abu Bakar, H.Ouyang, S. James, L.Li, D.C.Barton

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

Volume: 222, Number 7 / July 2008 Pages 1153-1165

DOI: 10.1243/09544070JAUTO536

Publisher: Professional Engineering Publishing

Abstract:

In the past, wear at the pad interface of disc brakes has rarely been accounted for in studies of brake squeal using the finite element method, and its effect on disc brake squeal has been investigated largely through experimental methods. In the present paper, wear taking place at this interface over time is simulated using a modified wear rate formula. The surface topographies of two new and unworn pairs of brake pads are measured. The same brake pads are tested under braking applications of three time durations. For each braking application, the static contact pressure distribution is measured using pressure-indicating film. The results are used to compare with the simulated results predicted by the three-dimensional finite element model of a real disc brake.

The paper also investigates squeal generation due to the above braking applications using complex eigenvalue analysis that is available in a commercial software package. It is found that the predicted unstable frequency is very close to the observed squeal frequency and that they take place in the same braking duration.

Title: Modelling and ride dynamics of a flexible multi-body model of an urban bus

Author(s): G Georgiou, A Badarlis, S Natsiavas

Source: Proceedings of the I Mech E Part K Journal of Multi-body Dynamics

Volume: 222 part 2, pages 143-154, April 2008

DOI: 10.1243/14644193JMBD130

Publisher: Professional Engineering Publishing

Abstract:
Dynamic response of a large order mechanical model of an urban bus is investigated in this paper. The emphasis is first put on developing a quite complete model, which can be utilized in order to extract sufficiently reliable and accurate information related to its dynamics in a fast way. Since some of the components of the bus undergo large rigid body rotation, in addition to motion resulting from their deformability, a multi-body dynamics framework is adopted. This implies that the resulting equations of motion appear in the form of a strongly non-linear set of differential-algebraic equations, which are difficult to handle even numerically. In fact, the modelling becomes more involved because all the significant non-linearities appearing in the interconnections of the structural components and especially in the front and rear suspension subsystems of the bus are taken into account. In order to alleviate some of these complexities, the number of degrees of freedom of each component, associated with its deformability, is reduced drastically by applying an appropriate coordinate condensation methodology. Finally, this model is employed and numerical results are obtained for motions resulting from typical road excitation. In particular, selected response quantities related to ride comfort are examined for characteristic combinations of the bus suspension stiffness and damping parameters.

Title: Regenerative braking strategy for hybrid electric vehicles based on regenerative torque optimization control

Author(s): F. Wang, B. Zhuo

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

Volume: 222, Number 4 / April 2008 Pages 499-513

DOI: 10.1243/09544070JAUTO654

Publisher: Professional Engineering Publishing

Abstract:
A regenerative torque distribution (RTD) strategy is proposed to make maximum use of the braking energy to improve fuel economy for hybrid electric vehicles, in which the available regenerative braking force, the demand of the front wheel braking force, and the front wheel lock-up force are all explicitly taken into account. The actual front wheel cylinder pressure, which is reduced by the amount of the actual regenerative braking force, is supplied from the electronic hydraulic brake system. An emulated engine compression braking (EECB) is suggested during coasting, and the electric motor provides a negative torque to emulate the internal combustion engine drag torque to charge the ultracapacitor. In addition, a regenerative torque optimization strategy (RTO) is implemented to maximize the actual electric power recuperated by the ultracapacitor. The simulation results show that both the RTD with RTO and the EECB with RTO are able to offer improved ultracapacitor voltages.

Title: Fault diagnostics in power electronics-based brake-by-wire systems

Author(s): M A Masrur, H-J Wu, C Mi, Z-H Chen, Y L Murphey

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

Volume: 222 Page: 1-11. Jan 2008

DOI: 10.1243/09544070JAUTO385

Publisher: Professional Engineering Publishing

Abstract: A d.c.-motor-based brake-by-wire system is studied for the purpose of fault diagnostics of the power electronic switches. The voltage and current generated in the switching circuit under normal and six faulted conditions are observed. A hierarchical fuzzy diagnostic system has been developed to detect certain types of fault condition in any specific solid state power switch at the moment immediately after the occurrence of the fault. The hierarchical fuzzy diagnostic system has been tested and validated using data from both a simulation and a laboratory set-up with a 1 / 3 hp d.c. motor and a d.c.-to-d.c. converter. The system performance has been compared with two different fuzzy diagnostic systems and the results are presented. The hierarchical fuzzy diagnostic system trained on the simulated model has the capability of detecting certain types of fault condition occurring in a brake-by-wire actuator system set-up in a laboratory in less than 0.0009 s and pinpointing the specific types of fault within less than 0.013 s.

Title: Optimal brake torque distribution for a four-wheeldrive hybrid electric vehicle stability enhancement

Author(s): D-H Kim, J-M Kim, S-H Hwang, H-S Kim

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

Volume: 221, Number 11 / November 2007 Pages 1357-1366

DOI: 10.1243/09544070JAUTO352

Publisher: Professional Engineering Publishing

Abstract:
Vehicle stability control logic for a four-wheel-drive hybrid electric vehicle is proposed using the regenerative braking of the rear motor and an electrohydraulic brake (EHB). To obtain the optimal brake torque distribution between the regenerative braking and the EHB torque, a genetic algorithm is used. The genetic algorithm calculates the optimal regenerative braking torque and the optimal EHB torque for the given inputs of the desired yaw moment and road friction coefficient. Based on the optimal brake torque distribution, the vehicle stability control logic proposed generates the desired direct yaw moment to compensate the errors of the side-slip angle and yaw rate by a fuzzy control algorithm corresponding to the driver's steering angle and vehicle velocity. Performance of the vehicle stability control logic is evaluated by comparison of the fixed regenerative braking and the optimal regenerative braking for a single lane change manoeuvre. It is found from the simulation results that the optimal regenerative braking is able to provide the increased recuperation energy compared with the fixed regenerative braking while satisfying the vehicle stability.

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

Author(s): Jeonghoon Song, Heungseob Kim, Kwangsuck Boo

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

Volume: 221, Number 7 / July 2007 Pages 777-787

DOI: 10.1243/09544070JAUTO225

Publisher: Professional Engineering Publishing

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.

Title: A study of commercial vehicle brake judder transmission using multi-body dynamic analysis


Author(s): K Hussain, S H Yang, A Day

Source: Proceedings of the I MECH E Part K Journal of Multi-Body Dynamics

Volume: 221, Number 2 / 2007 Pages 311-318

DOI: 10.1243/1464419JMBD23

Publisher: Professional Engineering Publishing

Abstract:
Braking-induced forced vibration, known as brake judder in road vehicles, causes dissatisfaction to drivers and passengers and also damage and possible early failure in components and systems. In this paper, the transmission of judder vibration from the point of generation (the brake friction pair) through the vehicle structure to the driver is investigated for the particular case of a heavy commercial vehicle. The investigation uses a computer simulation multi-body dynamic model based on the automatic dynamic analysis of mechanical systems software to identify any characteristics of the vehicle suspension design that might influence the vibration transmission from the wheel to the driver.

The model uses a simplified rigid chassis and cab to lump the chassis parameters, so that the investigation can focus on the front axle/suspension design, which is a beam axle leaf spring arrangement, and the rear axle/suspension assembly, which is a tandem axle bogie design. Results from the modelling indicate that brake judder vibration is transmitted to the chassis of the vehicle through a leaf spring ‘wind-up’ mode and a ‘walking’ mode associated with the rear tandem axle. Of particular interest is the longitudinal vibration transmitted through the chassis, since this creates a direct vibration transmission path to the cab and driver. The simulation results were compared with the previously published experimental work on the same design of commercial vehicle, and agreement between the predicted and the measured vibration characteristics and frequencies was found.

It is concluded that the rear suspension design parameters could affect the transmission of brake judder vibration to the cab and driver and that a tandem rear axle offers some design opportunity to control the transmission of brake judder vibrations from the wheel to the cab and driver. Given that brake judder has so far defied all attempts to eliminate completely from vehicle brake systems, this is potentially an important opportunity.

Title: Integrated control of suspension and front steering to enhance vehicle handling


Author(s): C. March, T. Shim

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

Volume: 221, Number 4 / 2007 Pages 377-391

DOI: 10.1243/09544070JAUTO152

Publisher: Professional Engineering Publishing

Abstract: Integration of vehicle chassis control system has gained increasing attention since it can improve the vehicle safety and performance through effective coordination of individual control systems. This paper presents the development of an integrated control system of active front steering and normal force control using fuzzy reasoning to enhance the vehicle-handling performance. Individual control systems were first developed, and then their performances were compared with that of the integrated system. The simulation results indicate that the integrated chassis control scheme utilizing the steering and suspension controllers has proven to be more effective in attaining the desired performance that would not be attained individually.

Title: Standard multi-body system software in the vehicle development process

Author(s): E. Fischer

Source: Proceedings of the I MECH E Part K Journal of Multi-Body Dynamics

Volume: 221, Number 1 / 2007 Pages 13-20

DOI: 10.1243/1464419JMBD59

Publisher: Professional Engineering Publishing

Abstract: In the developmental processes of a complex product, such as a passenger car, simulation software tools are used today to such an extent that the notion of a ‘virtual development process’ is justified, paralleling the hardware-based development process. In conjunction with several other software tools, a multi-body software system (MBS) can be an integral part of the virtual process, covering the area of suspension analysis and vehicle dynamics, provided it is tailored to the specific needs of the product, the software users, and the industrial organization. This article describes these needs by showing the context in which MBS is used, its interface with other tools, and the expectations of the users and concludes with an assessment of the current state.

Title: Structural analysis of steering wheel grip comfort by the semantic differential method

Author(s): K Nishina, M Nagata, N Ishii

Source: Proceedings of the I MECH E Part I Journal of Systems and Control Engineering     
Volume: 220 Page: 675-681. Nov 2006

DOI: 10.1243/09596518JSCE145

Publisher: Professional Engineering Publishing

Abstract: Kansei quality varies with the individual. Therefore, when building a structural model of Kansei quality, it is very important to identify some essential structures by analysing individual differences. In this paper, the semantic differential method is used to improve steering wheel grip comfort. Assuming a hierarchical structural model of the steering wheel grip comfort, the individual differences are analysed using principal component analysis, and then some hierarchical structural models are built using graphical modelling. As a result, two remarkably different structures are built. Some guidelines for developing steering wheel production can be shown by comparing the different structures.