  This paper presents a control reconfiguration approach to improve the
performance of two classes of dynamical systems. Motivated by recent research
on re-engineering cyber-physical systems, we propose a three-step control
retrofit procedure. First, we reverse-engineer a dynamical system to dig out an
optimization problem it actually solves. Second, we forward-engineer the system
by applying a corresponding faster algorithm to solve this optimization
problem. Finally, by comparing the original and accelerated dynamics, we obtain
the implementation of the redesigned part (the extra dynamics). As a result,
the convergence rate/speed or transient behavior of the given system can be
improved while the system control structure is maintained. Internet congestion
control and distributed proportional-integral (PI) control, as applications in
the two different classes of target systems, are used to show the effectiveness
of the proposed approach.
