1. Faculty of Electronic and Information Engineering, West Anhui University, Lu’an 237012, P. R. China
2. Anhui Undergrowth Crop Intelligent Equipment Engineering Research Center, West Anhui University, Lu’an 237012, Anhui, P. R. China
3. Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, Anhui, P. R. China