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Title: An automatic gear-shifting strategy for manual transmissions

Author(s): B Mashadi, A Kazemkhani, R Baghaei Lakeh


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

Volume: 221, No 5 Page: 757-768. August 2007

DOI: 10.1243/09596518JSCE253

Publisher: Professional Engineering Publishing

Abstract: Based on two different criteria, namely the engine working conditions and the driver's intention, the governing parameters in decision making for gear shifting of an automated manual transmission are discussed. The gear-shifting strategy was designed by taking into consideration the effects of these parameters, with the application of a fuzzy control method. The controller structure is formed in two layers. In the first layer, two fuzzy inference modules are used to determine the necessary outputs. In the second layer a fuzzy inference module makes the decision of shifting by upshift, downshift, or maintain commands. The behaviour of the fuzzy controller is examined by making use of ADVISOR software. It is shown that at different driving conditions the controllers make correct decisions for gear shifting accounting for the dynamic requirements of the vehicle. It is also shown that the controller based on both the engine state and the driver's intention eliminates unnecessary shiftings that are present when the intention is overlooked. A microtrip is designed in which a required speed in the form of a step function is demanded for the vehicle on level or sloping roads. Both strategies for the vehicle to reach the maximum speed starting from rest allow the gear shift to be made consecutively. Considerable differences are observed between the two strategies in the deceleration phase. The engine-state strategy is less sensitive to downshift, taking even unnecessary upshift decisions. The state intention strategy, however, interprets the driver's intention correctly for decreasing speed and utilizes engine brake torque to reduce the vehicle speed in a shorter time.

Title: Static and dynamic characteristics of a hybrid aluminium/composite drive shaft

Author(s): S A Mutasher, B B Sahari, A M S Hamouda, S M Sapuan

Source: Proceedings of the I MECH E Part L Journal of Materials: Design and Applications

Volume: 221, No 2 Page: 63-75. April 2007

DOI: DOI 10.1243/14644207JMDA63

Publisher: Professional Engineering Publishing

Abstract: A static torque and power transmission capacities of a hybrid aluminium/composite drive shaft, fabricated by a wetted filament winding method, were investigated. Special mechanisms for static torsion and power transmission test setups were designed and fabricated. The following different fibre types were used: carbon, glass, one epoxy, and hardener. The static and dynamic characteristic of the hybrid aluminium/composite drive shaft with respect to the fibre types stacking sequences winding angle and number of layers were investigated. From the experiments, it was found that the static and dynamic torque capacity for a winding angle of 45° is higher than 90° for both glass and carbon fibres. From the power transmission test, it was also found that the percentage between the static torque and dynamic torque is approximately 7-15 per cent. In addition, in the static torsion test, the aluminium tube yielded first at the central region of the shaft, followed by crack propagation in the composite shaft along the fibre direction, which eventually caused the delamination of the composite layers from the aluminium tube. On the other hand, in the power transmission test, different locations of failure were observed along the gauge length of the specimen. The shaft's being laminated with a stacking sequence of [90/ + 45/-45/90] and [+45/ -45/90/90] resulted in the same behaviour in the torque-angle and the twist relation. The power transmission capacities were close to each other and this in turn satisfied the lamination theory. The finite-element method was used to analyse the hybrid shaft under static torsion and ANSYS finite-element software was used to perform the numerical analysis for the hybrid shaft. A full scale hybrid specimen analysis was done. Elasto-plastic properties were used for the aluminium tube and linear elastic for composite materials. Good agreement was obtained between the finite-element predictions and experimental results.

Title: Coordination of active steering, driveline, and braking for integrated vehicle dynamics control

Author(s): Junjie He, D A Crolla, M C Levesley, W J Manning

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

Volume: 220 Pages: 1401-1420. October 2006

DOI: 10.1243/09544070JAUTO265

Publisher: Professional Engineering Publishing

Abstract: An integrated vehicle dynamics control system which aims to improve vehicle handling and stability by coordinating active front steering (AFS) and dynamic stability control (DSC) subsystems is developed in this paper. The DSC subsystem includes driveline-based, brake-based, and driveline plus brake-based DSC subsystems. The influence of varying forward speed and lateral acceleration on the lateral vehicle dynamics is investigated first. The AFS controller, which is used to improve vehicle steerability in the low to mid-range lateral acceleration, and the DSC controller, which manages to maintain vehicle stability during extreme driving situations, are then designed by using the sliding mode control (SMC) technique and phase plane method respectively. Based on the two independently developed controllers, a rule-based integration scheme is proposed to optimize the overall vehicle performance by minimizing interactions between the two subsystems and extending functionalities of individual subsystems. Computer simulation results confirm the effectiveness of the proposed control system and the overall improvements in vehicle handling and stability.

Title: Effects of Design Parameters on the Slipping Torque of an Overrunning Clutch

Author(s): Yung-Chuan Chen, Li-Wen Chen

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

Volume: 220 Page: 563-570. May 2006

DOI: 10.1243/09544070JAUTO27

Publisher: Professional Engineering Publishing

Abstract: In this study, both finite element analysis and experimental tests are conducted to explore the effects of design parameters on the slipping torque of overrunning clutches. The parameters discussed are: the friction coefficient, the tolerance of roller radius, the eccentric of the outer ring, and the number of rollers. Contact elements are used to model the contact between rings and rollers in finite element analyses. The experimental results are compared with the simulation results and are used to estimate the friction coefficient used in the finite element analysis. The results indicate that the friction coefficient, tolerance of roller radius, eccentric of outer ring, and number of rollers significantly affect the slipping torque. This study has also proposed a set-up for experimental tests of overrunning clutches.

Title: Analysis and simulation of clutch engagement judder and stick-slip in automotive powertrain systems

Author(s): A Crowther; N Zhang; D K Liu; J K Jeyakumaran

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

Volume: 218 Page: 1427 - 1446. December 2004

DOI: 10.1243/0954407042707731

Publisher: Professional Engineering Publishing

Abstract: Clutch engagement judder and stick-slip are investigated analytically and numerically to examine the influencing factors on these phenomena. Models are developed for a four degree-of freedom (4DOF ) torsional system with slipping clutch and for a powertrain with automatic transmission system. Stability analysis is performed to demonstrate that clutch judder is dependent on the slope of the friction coefficient and the analysis is verified with numerical simulations. An algorithm for modelling stick-slip is developed and is used in numerical simulations which show that the likelihood of stick-slip is increased by clutch pressure fluctuations, judder approaching engagement, and external torque fluctuations. Numerical simulations for second to third gear up shifts demonstrate that the likelihood of stick-slip to occur from clutch engagement is increased by clutch applied pressure fluctuations, judder approaching engagement, and external torque fluctuations and that the likelihood of stick-slip occurring is decreased dramatically by applied pressure ramps proximus to the engagement point.