Though PID control has a long history as much as its life force since Ziegler
and Nichols published the empirical tuning rules in 1942, surprisingly, it has
never been changed in the structure itself. The strength of PID control lies in
the simplicity, lucid meaning, and clear effect. Though it must be a widely accepted
controller for mechanical control systems, it is still short of theoretical
bases, e.g., optimality, performance tuning rules, automatic performance tuning
method, and output feedback PID control have not been clearly presented
for mechanical control systems. These subjects will be thoroughly discussed in
this book. There are many books of PID controller for the purpose of process
control, but it is hard to find a book on the characteristics of PID control for
mechanical systems.