1. Dept of Mech Eng, Louborough Univ, Louborough, Leicestershire, LE11 3TU, UK
2. Inst of Machine Stud, Russian Acad of Sci, Moscow, 101830, Russia
3. Dept of Mech Eng and Center for Intelligent Machines, McGill Univ, 817 Sherbrooke St W, Montreal, PQ, H3A 2K6, Canada