The ERS-1100 is a rare version of the ERS-110 that was made exclusively for projects like RoboCup’s Four Legged League in 1999 and 2000.
In 2000, 12 different groups competed, for a total of at least 36 ERS-1100 robots existing.
It’s not known if many of these special pups are still around, but one is known to have spent some time at the AIBO Ranch in California!
If you look closely at the image you can see the rectangular panel in the middle of the ERS-1100′s back isn't fixe like it is in a 110 and is removable. There is also a covered plug on the back of 1100’s head. With these modifications, the RoboCup teams could connect Aibo to a computer to view data and get a better understanding of how Aibo interacts with and sees the world.
In a book published by one of the teams they go into detail about the challenges they faced due to the narrow field of vision and limited external sensor inputs and also the limited cpu compute performance to enable self driven free roaming commands.
Try to remember this was in the days that a self driving car was still in the realm of science fiction and there they were making consumer level robot companions play autonomous football. Quite an achievement really.
The blue battery next to this pup was made exclusively for the ERS-1100. Not much is known about it or what exactly makes it different from a normal first generation AIBO battery other than the labels and color being different, but these batteries are as hard to find secondhand as the robots that use them.