L2t exception

Immediately after initializing the system

Check if there are no external forces or obstacles that can affect your motor. If not, then it indicates a hardware problem with the corresponding motor.

During calibration

The calibration current limit for the joint in the configuration file of the manipulator is to high. Reduce the value for that joint, which throws the exception during the calibration.

 gedit ....../youbot_driver/config/youbot-manipulator.cfg 

set the calibration max current to a lower value

 CalibrationMaxCurrent_[ampere] = x.y