1. Department of Electrical and Electronic Engineering, College of Technology (COT), University of Buea 1 , P.O. Box 63, Buea, Cameroon
2. Centre for Nonlinear Systems, Chennai Institute of Technology 2 , Chennai 600069, India
3. Electronics and Communication Engineering, Vemu Institute of Technology 3 , Chittoor 517112, India
4. Department of Automation, Biomechanics and Mechatronics, Lodz University of Technology 4 , ul. Stefanowskiego 1/15, Lodz 90-537, Poland