Our lead servo engineer (and a lot of people in the industry) were strongly influenced by Franklin, Powell, and Workman's book "Digital Control of Dynamic Systems," and IIRC there's a chapter devoted to disk drive control systems in it.
I worked a bit on the seek algorithms, but I also worked on the repeatable-runout cancellation system, which was actually a lot cooler to work on but less interesting to most people. It basically did Fourier Transforms to compute "predictable" errors staying over the track caused by things like disk shift or "potato chipping" of the disks. That error could then be injected back into the voice-coil motor to help keep the heads in the right place.
It was all written in a very low level assembly language on a custom ASIC we designed in-house with no floating point arithmetic. :) That was almost 20 years ago at the very beginning of my career and it's still some of the coolest code I've ever written. :-/
Our lead servo engineer (and a lot of people in the industry) were strongly influenced by Franklin, Powell, and Workman's book "Digital Control of Dynamic Systems," and IIRC there's a chapter devoted to disk drive control systems in it.
I worked a bit on the seek algorithms, but I also worked on the repeatable-runout cancellation system, which was actually a lot cooler to work on but less interesting to most people. It basically did Fourier Transforms to compute "predictable" errors staying over the track caused by things like disk shift or "potato chipping" of the disks. That error could then be injected back into the voice-coil motor to help keep the heads in the right place.
It was all written in a very low level assembly language on a custom ASIC we designed in-house with no floating point arithmetic. :) That was almost 20 years ago at the very beginning of my career and it's still some of the coolest code I've ever written. :-/