1. Intelligent Control Group, Centre for Automation and Robotics UPM–CSIC, Universidad Politécnica de Madrid, C/J. Gutiérrez Abascal, 2, 28006 Madrid, Spain
2. Department of Electrical, Electronics, Control Engineering and Applied Physics, School of Industrial Design and Engineering, Universidad Politécnica de Madrid, C/Ronda de Valencia, 3, 28012 Madrid, Spain