This paper discusses the importance of having an adequate model for the dynamic response characteristics of tire lateral force to steering inputs. Computer simulation and comparison with experimental results are used to show the importance of including appropriate tire dynamics in simulation tire models to produce accurate predictions of vehicle dynamics.
Improvements made to the tire dynamics model of an existing vehicle stability and control simulation, the Vehicle Dynamics Analysis, Non-Linear (VDANL) simulation, are presented. Specifically, the improvements include changing the simulation's tire dynamics from first-order system tire side force lag dynamics to second-order system tire slip angle dynamics.
A second-order system representation is necessary to model underdamped characteristics of tires at high speeds.
Lagging slip angle (an input to the tire model) causes all slip angle dependent tire force and moment outputs to be lagged. This is a better representation of the actual physical system than merely lagging the tire side force.
The modified tire dynamics were implemented into VDANL, which improved simulation predictions in both the time and frequency domains.