The role of the tyre is discussed in view of actively controlling the motion of the road vehicle. Several control objectives are considered, while distinction is made between the objectives which are meant to maintain stability, improve handling and reduce effects of disturbances and those which may widen the margin of safe operation of the car. To properly design control algorithms, knowledge of tyre properties is a requirement. In this regard, mathematical models of the tyre as a force and moment generating vehicle component are discussed. To gain insight, the simple brush tyre model is treated first. Then the steady state empirical Magic Formula tyre model follows with some elaboration on the next release. Finally, the non-steady state behaviour of the tyre is treated. The relatively simple model that is restricted to low time and path frequencies, is based on first order differential equations featuring the relaxation lengths for longitudinal and lateral wheel transient motions. Some discussion is added on required model extensions to allow a wider range of operation. (A)
Abstract