www.uvvu.com is a frequent add-on to many titles.
However, unless you buy a new Blu-Ray with this option, how do you manage to enjoy your bought DVD collection on your phone or tablet? And what is the legality of converting your own DVD's to view on your own devices, without sharing it? The legal term is know as "space-shifting" as as long as you are the only one viewing it, once at a time, it appears to be legal.
There are lots of copy protection schemes built into DVD's these days. One good option is to use DVDFab at www.dvdfab.com simply to copy the main title onto your hard drive (VOB files). Then you can usually use HandBrake to convert the file down to any format you like (www.handbrake.fr). Usually just using "Normal" should do the trick and convert into an mp4 file of good quality. It seems using HandBrake directly for the copying leads to bad corrupt movies that are simply unviewable. However, copying the VOB's to your hard drive with DVDFab (or other copy software) strips some of the copy protection schemes to allow you to properly convert in HandBrake. Of course, you can also do the conversion directly in DVDFab but if you are looking for a free option this combination may do the trick.
Just one last note... It takes a long time to copy, then to convert... We are talking hours (at least on my setup). So it may not be worth it. As well, DVDFab only has a 30 day trial, but at least you can see how it works before buying it (it has many other features). There may be other VOB copying software that strips copy protection in the open-source/free community. Finally, not all DVD's work. I found many Disney titles almost impossible to copy, and others gave corrupt reading errors (yet they play fine on a DVD player). Have fun and stay legal!