I didn't work on hexapod, but one of my friend worked on it. However, he didn't write his thesis in English but Vietnamese.
But here is a link to download some useful PhD thesis on many fields. You may pay a visit to this to find the suitable documents.
**broken link removed**
I don't remember if there is any thesis on hexapod, but it's valuable to skim around.
Hexapod give a difficult kinetics, but if you understand clearly about DH matrix, you can solve it. We usually use hydraulic suppliers to control the hexapod.
Goodluck.