1. Vehicle Dynamics and Active Safety, Volvo Car Corporation, SE-405 31 Gothenburg, Sweden; KTH Vehicle Dynamics, SE-100 44 Stockholm, Sweden e-mail:
2. Modelon AB, Ideon Science Park, SE-223 70 Lund, Sweden
3. Vehicle Dynamics and Active Safety, Volvo Car Corporation, SE-405 31 Gothenburg, Sweden
4. KTH Vehicle Dynamics, SE-100 44 Stockholm, Sweden