We’ve found two really great books on our topic in our amazing library (we have everything really, haptics is an obscure field).

The first is Engineering Haptic Devices: a Beginner’s Guide for Engineers. Everything is broken down, the design criteria for the physical plant is laid out, making designing a haptic device simply following a check list. Pseudocode for the virtual wall algorithm is covered in chapter 13. We really encourage any group wanting to do a haptics project to read this book.

Next there is Cable-Driven Parallel Robots. Page 345 has a planar design similar to ours and the associated controller.