It's always a bit of a stab in the dark with these Excel files, but we can only assume that the robot in question is unable to "take a picture." When working in Excel, I always try to be as vague as possible to cover as many options as I can, hence the "take a visual image." You could vague it out even further by saying "unable to obtain a visual image." That way you cover the options of inability to capture or record a photo due to hardware or software issues, as well as physical blocking of the line of sight of whatever cameras or sensors it's using.