You need to run some commands to calibrate the robot after you connect and go online with it.
Usually there are two calibrations needed for cobra robot: rough cal and fine cal. You can do rough cal by typing the command. But you do need a set of special jig to do the fine cal.
Thank you so much for your reply ! I have a quick question if you don't mind. When I tried to rough calibrate, I got overflow alarms from every encoder ( I've checked the encoder readings they are indeed very big ), so I wanted to clear the encoder data first. And from a pdf named "Instructions for Adept Utility Programs" I've found a utility called "ABS_ENC.V2", which can be used to clear encoder error/alarm. But this only works for AdeptVicron robot, not for AdeptViper. I couldn't find other utilities that do the same job for the Viper robot. I'd like to ask what utility you use to clear encoder error/alarms ? Thanks again!