Personal Mobility Device - motor technology?
If this is something you want to build fast, and get it working, then KISS is the only way to go, Keep It Simple StupidSoYouDontHaveLongDevelopmentTime.

Battery - SLA sealed lead acid - tame, easy to charge
Motors - DC peramanent magnet - tame, easy to control
Controllers - buy something like 4QD (other makes are available) - don't design and build H bridges from scratch
Wheels/Gears - buy a 'motor with a reduction gearbox to a wheelchair wheel' in one assembly, rather than start bolting and milling and mounting