Active Control of Driveability

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. Significant improvements to vehicle driveability are demonstrated on a complex non-linear model of a vehicle powertrain during acceleration and deceleration manoeuvres. This technique permits greater design freedom, when compared with passive approaches, over the choice of powertrain components that affect driveability.