A capacitive sensor assembly for a robot to prevent damage to the robot when it moves in an undesired manner is disclosed. The robot may be used in conjunction with semiconductor fabrication applications. The capacitive sensor assembly can include a hit contact, one or more fixed contacts, one or more damping springs, and a capacitive sensor. The hit contact comes into contact with a barrier as a result of undesired movement by the robot. The damping springs are compressed against the fixed contacts when the hit contact comes into contact with the barrier. The capacitive sensor has a capacitance that changes as the hit contact comes into contact with the barrier. The capacitance of the capacitive sensor is used to detect the robot coming into contact with the barrier, so that damage to the robot can be prevented.