1. Department of Information Technology, University of Huelva, Carretera Palos de La Frontera s/n, 21819, Palos de la Frontera, Huelva, Spain. E-mail: npavon@dti.uhu.es
2. Department of Electronics Technology, Technical University of Cartagena, Campus Muralla del Mar, s/n, 30202 Cartagena, Murcia, Spain. E-mail: jantonio.lopez@upct.es
3. Robotics, Vision and Control Group, University of Seville, Camino de los Descubrimientos, s/n, 41092 Seville, Spain. E-mail: ferruz@cartuja.us.es, ajosebarrios@gmail.com
4. ARCO Research Group, University of Extremadura, Escuela Politécnica. Campus Universitario s/n, 10003 Cáceres, Spain. E-mail: mavega@unex.es