Developments in On-Centre Steering Evaluation and Testing

Traditionally on-centre steering has been evaluated by a sine wave steering input through-centre. This method is widely used to characterise the on-centre steering characteristics of vehicles. Although it enables a wide range of key parameters to be quantified such as on-centre stiffness and hysteresis, the test does not encompass how the vehicle responds when an input is made from or returning to the straight running condition.

The objective of this study was to propose additional on-centre evaluation methods that would include the response of the car from straight ahead running. A range of vehicles were then tested in accordance with these methods using a combined IMU/GPS system.

The data from this testing was analysed to determine what measures might be useful in quantifying the response of a vehicle from straight ahead running. Then using the data obtained from this group of vehicles provide reference information on the upper and lower limits of these measures.