One of the key components of the cable robot is understanding the forward and inverse kinematics. Lucky for us there a great resource out there that already exists. For this robot I used emc2 which I use to control my CNC Mill and CNC router. That can be found at the following location -> EMC2 (now linuxcnc). Typically that software is used to control mills and lathes that are orthogonal in nature, XYZ style setups. However if you dig into it you find out that it supports different kinematics such as a cable robot. The real beauty resides in this file called tripodkins.c. If you want to make your head hurt a little you can try to derive it out, kind of fun.