[1] Univ Deusto, Dept Comp Elect & Commun Technol, Bilbao 48007, Spain
[2] Univ Deusto, Dept Mech Design & Ind Management, Bilbao 48007, Spain
[3] Univ A Coruna, Dept Ind Engn, CTC, La Coruna 15403, Spain
[4] Univ Salamanca, Dept Comp Sci & Automatic, Salamanca 37008, Spain