04-02-2013, 10:19 AM
Underdamped Second-Order Systems Overshoot Control
1Underdamped Second-Order.pdf (Size: 1.79 MB / Downloads: 79)
Abstract:
The paper addresses the problem of decreasing the overshoot for underdamped second-order
systems. A new technique to control the overshoot is proposed, which is based on Posicast control and
proportional integral and derivative (PID) control, which performs switching between two controllers.
The aim is to use open-loop feedforward control to increase tracking performance and PID control to deal
with disturbance rejection. It has been shown that the proposed control scheme can have some
advantages over the classical approaches without switching capabilities.
INTRODUCTION
A deadbeat-response is often considered as an optimal
closed-loop response, since it achieves minimum rise-time,
no steady-state error and no overshoot, in a minimum number
of time-steps. From the authors’ experience in designing
second-order systems control, an important question is: how
to achieve small or zero overshoot in the closed-loop stepresponse
for the second-order systems? This is a relevant
issue, as there are many control applications in practice
dealing with systems dynamics represented by second order
models and requiring minimum overshoot. The
representatives of such systems can be found in robot control
(Singhose and Seering, 2005), crane control (Sorensen et al.,
2007) vibration control (Singer and Seering, 1990; Singhose,
2009; Singh and Singhose, 2002; Dhanda and Franklin, 2005)
and power-systems electronics (Li, 2009; Chiang et al.,
2009).
FEEDFORWARD-FEEDBACK PID CONTROL
Most of the industrial control loops are controlled either by
proportional and integral (PI) controllers or by proportional,
integral and derivative (PID) controllers (Åström and
Hägglund, 1995) due to a relatively high performance and
robustness levels achieved in a wide range of plants. This
type of controllers can be represented and implemented using
several control configurations (Araki and Taguchi, 2003).
This study considers PID control implemented with output
filter, since controller output activity is significantly reduced
in noisy systems (Vrančić et al., 2005).
CONCLUSIONS
A new technique was proposed which integrates the halfcycle
shaper as a feedforward compensator to increase
tracking performance and a PID controller to retain
disturbance rejection properties. The transition between the
manual feedforward set-point operation and automatic
feedback PID control is accomplished by using an
appropriate anti-windup and bumpless transfer technique.
The proposed solution is especially efficient for decreasing
the overshoots of underdamped second-order systems.
Simulation results clearly indicate that the Posicast technique
significantly improves the set-point tracking performance
compared to the PID controller.