A scientist on a remote planet creates a simple robot to help him. He then makes more and they become able to improve themselves and build even more, until they populate a large city, which is then run by a master computer. They isolate themselves with a fully enclosed wall that is patrolled by very large dome shaped centurion robots that move with metallic octopus like legs and can fire lasers from a single eye.
An aggressive society from another planet decides to attack the robot city/planet and are annihilated as the robot space ships have shields and destructive laser beam weapons. The attackers do not have defensive shields against the robot weapons. The attackers come from a planet called Cassiopeia (I think) and are lead by a large, bulbous nosed leader who has a henchman with spiked red hair.
The animation is likely from early 80s or even 70s. Maybe an American made movie, but the sound is English (maybe dubbed). I don't remember the plot of the movie, but the story includes detailing how the robot city started from the scientist and grew into a large society. The scientist is hailed by the robots as their leader, as they embark to carry out his original wish (can't remember what that was).
Can't remember that film's name? Post the plot, and see if other users can help.