What you are looking for is a robotic pool cleaner.

Here is my experience with them-others may be different

Aquabot turbo-excellent cleaner, works well in cold water(cleans pool in spring startup), lasts a long time, parts readily available. A real workhorse

Dolphin Diagnostic- Cleans well, remote is a nice feature, does not work in cold water and is not reliable. When it does breakdown customer support is poor.

Aquabot Viva-my present cleaner- works very well, cleans pool in about an hour if you do bottom only, remote works well...still working after 3 years with no service.

Another cleaner people speak highly of is the blue diamond.

Do some research and check out eBay for some good pricing.

Hope this helps

Zane