The CRB-S are giant robot dogs, quite a bit larger than their cyberdog cousins. Designed for non-lethal (in theory) containment of Denver's revolting population, three of these units were in use by the Denver City police department prior to the deployment of the National Guard.
One of Dog Town's quests is to get rid of these three robots, as they would continue to harass the player. An alternative is to reprogram one of them to follow the player as a companion (but only within Denver city limits) or to change the priorities of the robots and use them to drive out the dogs roaming the city, salvagers, Caesar's legionaries, etc.
Some details and special attacks, from the Dog Town design doc:
DISARM: If the player has a weapon in their hands, they will seek to disarm the player with their attacks.
RADIO CONTROL: They can communicate with each other via radio; this needs to be shut down if the players want to cause the CERBERUS units to start acting blindly.
LIMITED HEALING: They cannot repair in-between battles, and they can't at all if their robot cradles are damaged in the DCPD Canine Division.
WARNING: There will be a crackling for one round before they attack.
SUBDUE: If they are attacked, they will do anything in their power to subdue the first attacker and they will take him to the nearest jail cell.
ATTACKS: They can fire tear gas clouds and canisters, but their housing chambers are empty. Other possible chambers:
Fire fighting foam cannons (foam, only against flame attacks)
Water cannons (2-15 Water)
Shock attacks (2-20 Electricity)
Name (Proto ID)
Disarm, foam cannon, flash grenades
Water cannon, shock attacks
Radio control, subdue
It also had the Bonus Move perk, giving it 2 extra movement AP's. Other than the skills listed on the right, it also had Van Buren-specific skills, namely Programs = 50%, Electronics = 25%, Mechanics = 80%. Its starting XP score was 1111.
The robotic dog companion concept was later reused for Fallout: New Vegas with Rex as they share background but in the finalized concept, he is a normal-sized dog and is not stated to be deployed for a revolting population.
CRB-S is named after Cerberus, a giant, three-headed dog who guards the gates of the Underworld, to prevent those who have crossed the river Styx from ever escaping.
The design document used a still shot from Red Planet (2000) to conceptualize the CRB-S, showing AMEE, the movie's robotic companion and eventually menace. The shot is taken from the introduction scene.