Abstract:
ABSTRACT
FUZZY LOGIC PD CONTROL OF A NON-LINEAR INVERTED
FLEXIBLE PENDULUM
by
Kou A. Kong
Master of Science in Electrical and Computer Engineering
Electronic Engineering Option
California State University, Chico
Summer 2009
In automatic control systems, an inverted pendulum is a classical system to
be controlled. The inverted pendulum is more complex and complicated to control when
flexibility is present in the pendulum. Flexibility in the system can cause a system to be
unstable. In this project, an intelligent fuzzy proportional-derivative (PD) control is proposed
to control the flexible inverted pendulum. The flexible inverted pendulum is
modeled in non-linearity using Euler-Lagrange energy method. The fuzzy proportionalderivative
(PD) control is compared with the classical PD control in this system. Even
though the classical PID control is widely used in industrial control systems, it will
break down in most non-linear systems.
The simulations of the flexible inverted pendulum are done in Simulink and
Matlab. The linear and nonlinear flexible inverted pendulums are simulated for six different
cases. The simulation results demonstrate the performance differences between the
classical PD control and fuzzy PD control. The classical PD control works for the linear
system in terms of oscillations and settling time for all step inputs and cases. On the
nonlinear system, the classical PD control has more oscillations in all three modes of vibrations
for the second and third step inputs. The fuzzy PD controller shows better system
responses and steady-state performances for the nonlinear system. The second and third
step inputs have fewer oscillations for all three modes of vibrations. The fuzzy PD controller
has a better overall performance because it has the ability to adjust the gain values
according to the system output response. On the other hand, the conventional PD controls
have a constant gain value for different system output responses. These results are integrated
in Chapter VI. It can also be seen by running the programs on the CD included
with this report. The instructions to simulate the programs on the CD are in the Read Me
Instructions in Appendix E.
