I'm new to robotics. I would like to know if 56 output lines can be taken from an arduino or raspberry pi?
From the Arduinos only the "DUE" will work. It has 54 Digital IOs and 2 Analog Outputs.
The newest raspberry has "only" 40 IOs, so it won't fit your specs.
Another possibility would be the "BeagleBone Black" with up to 69 IOs.