[1] Univ Pisa, Res Ctr E Piaggio, Pisa, Italy
[2] Univ Pisa, Dept Informat Engn, Pisa, Italy
[3] Newcastle Univ, Sch Engn, Newcastle Upon Tyne, England
[4] Univ Piemonte Orientale, IRCAD, Via Solaroli 17, I-28100 Novara, Italy
[5] Univ Piemonte Orientale, Dept Hlth Sci A Avogadro, Via Solaroli 17, I-28100 Novara, Italy