Thank you for your reply.
I afraid that I am not using Simonk ESC. The one that I use is ordinary ESC connected to brushed motor.
And after I searched through another Erle forum about ESC calibration problems, I found @imuguruza mentioned in one forum that APM firmware only support Simonk ESC (http://forum.erlerobotics.com/t/pxfmini-rpi0-not-entering-esc-calibration-mode/2446/14?u=warittha). Is that true?
Are there the way that I can continue using the ordinary ESC with brushed motor and do ESC calibration for it? Or do I need to change my rover components? I quite don't want to do it because this rover is belong to my advisor. I borrow it from him to do my senior project. Or if changing hardware the only way that I can do to fix this jerky running, can you provide me the detailed instruction to change the rover components to the correct one?