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Due to improving levels of vehicle refinement and the growing importance of vehicle sound quality, transmission whine is an issue of increasing interest to vehicle manufacturers. This paper describes the development of a set of novel tools for the prediction of gear whine from spur and helical external gear systems. Transmission whine is primarily generated by transmission error, which is a deviation of meshing gears from a perfectly conjugate (smooth) motion due to manufacturing tolerances, tooth corrections and elastic deflection due to transmitted torque. The transmission error excites the geared shaft and bearing system leading to dynamic forces at the bearings, which in turn excite the transmission casing causing it to radiate noise.

Modern vehicles require a high degree of refinement, including good driveability, to meet customer demands. Specific aspects of driveability can be improved through the use of modern control techniques. This paper describes work by Ricardo on a novel active driveability control algorithm to reduce unwanted fore and aft oscillations in vehicle acceleration, known as shuffle, following a change in accelerator pedal position. The control algorithm is derived from a linearized model of the vehicle drivetrain and comprises two elements; a state observer estimating values of unmeasurable variables in the powertrain from standard production sensors and a state feedback controller to modulate engine torque. Together, these two elements increase the damping factor of the powertrain at critical frequencies and hence reduce vehicle shuffle.